Measuring Transducer of Vibration-Type with Four Curved Measuring Tubes

ABSTRACT

The measuring transducer comprises: a transducer housing ( 7   1 ), of which an inlet-side, housing end is formed by means of an inlet-side, flow divider ( 20   1 ) having four flow openings ( 20   1A   , 20   1B   , 20   1C   , 20   1D ) and an outlet-side, housing end is formed by means of an outlet-side, flow divider ( 20   2 ) having four flow openings ( 20   2A   , 20   2B   , 20   2C   , 20   2D ); as well as a tube arrangement having four, curved, or bent, measuring tubes ( 18   1   , 18   2   , 18   3   , 18   4 ) connected to the flow dividers ( 20   1   , 20   2 ) for guiding flowing medium along flow paths connected in parallel, wherein each of the four measuring tubes opens with an inlet-side, measuring tube end into one of the flow openings of the flow divider ( 20   1 ) and with an outlet-side, measuring tube end into one the flow openings of the flow divider ( 20   2 ). The transducer further comprises an exciter mechanism for exciting oscillations of said measuring tube. The tube arrangement exhibits a natural bending oscillation mode, called V-Mode, and the exciter mechanism is adapted to excite bending oscillation in said V-mode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.12/971,515 filed on Dec. 17, 2010, which claims the benefit of U.S.Provisional Application 61/344,561 filed on Aug. 20, 2010; and also U.S.patent application Ser. No. 12/970,072 filed on Dec. 21, 2009 whichclaims the benefit of U.S. Provisional Application 61/282,132 filed onDec. 22, 2009 and claims the benefit of German Application DE 10 2010039 627.3 filed on Aug. 20, 2010 and German Application DE 10 2009 055069.0 filed on Dec. 21, 2009.

The invention relates to a measuring transducer of vibration-type formeasuring a medium flowably guided in a pipeline, especially a gas,liquid, powder or other flowable material, especially for measuring adensity and/or a mass flow rate, especially also a mass flow integratedover a time interval, of a medium flowing in a pipeline, at least attimes, with a mass flow rate of more than 1000 t/h, especially more than1500 t/h. Additionally, the invention relates to a measuring systemhaving such a measuring transducer, especially a measuring systemembodied in the form of an in-line measuring device.

Often used in process measurements, and automation, technology formeasuring physical parameters, such as e.g. the mass flow, the densityand/or the viscosity, of media, for instance, an aqueous liquid, a gas,a liquid-gas-mixture, a vapor, an oil, a paste, a slurry or anotherflowable material, flowing in pipelines are in-line measuring devices,which, by means of a measuring transducer of vibration-type, throughwhich medium flows, and a measuring, and operating, circuit connectedthereto, effect, in the medium, reaction forces, such as e.g. Coriolisforces corresponding with mass flow, inertial forces corresponding withdensity of the medium and/or frictional forces corresponding withviscosity of the medium, etc., and produce derived from these ameasurement signal representing the particular mass flow, viscosityand/or density of the medium. Such measuring transducers, especiallymeasuring transducers embodied as Coriolis, mass flow meters orCoriolis, mass flow/densimeters, are described at length and in detaile.g. in EP-A 1 001 254, EP-A 553 939, U.S. Pat. No. 4,793,191, US-A2002/0157479, US-A 2006/0150750, US-A 2007/0151368, U.S. Pat. No.5,370,002, U.S. Pat. No. 5,796,011, U.S. Pat. No. 6,308,580, U.S. Pat.No. 6,415,668, U.S. Pat. No. 6,711,958, U.S. Pat. No. 6,920,798, U.S.Pat. No. 7,134,347, U.S. Pat. No. 7,392,709, or WO-A 03/027616.

Each of the measuring transducers includes a transducer housing, ofwhich an inlet-side, first housing end is formed at least partially bymeans of a first flow divider having exactly two, mutually spaced,circularly cylindrical, or tapered or conical, flow openings and anoutlet-side, second housing end is formed at least partially by means ofa second flow divider having exactly two, mutually spaced, flowopenings. In the case of some of the measuring transducers illustratedin U.S. Pat. No. 5,796,011, U.S. Pat. No. 7,350,421, or US-A2007/0151368, the transducer housing comprises a rather thick walled,circularly cylindrical, tubular segment, which forms at least a middlesegment of the transducer housing.

For guiding the medium, in given cases, also an extremely hot, medium,which flows, at least at times, the measuring transducers include,furthermore, in each case, exactly two measuring tubes of metal,especially steel or titanium, which are connected such that the mediumcan flow in parallel and which are positioned within the transducerhousing and held oscillatably therein by means of the aforementionedflow dividers. A first of the, most often, equally constructed and,relative to one another, parallel extending, measuring tubes opens withan inlet-side, first, measuring tube end into a first flow opening ofthe inlet-side, first flow divider and with an outlet-side, secondmeasuring tube end into a first flow opening of the outlet-side, secondflow divider and a second of the measuring tubes opens with aninlet-side, first measuring tube end into a second flow opening of thefirst flow divider and with an outlet-side, second measuring tube endinto a second flow opening of the second flow divider. Each of the flowdividers includes additionally, in each case, a flange with a sealingsurface for fluid tight connecting of the measuring transducer totubular segments of the pipeline serving, respectively, for supplyingand removing medium to and from the measuring transducer.

For producing the above discussed reaction forces, the measuring tubesare caused to vibrate during operation, driven by an exciter mechanismserving for producing, or maintaining, as the case may be, mechanicaloscillations, especially bending oscillations, of the measuring tubes inthe so-called wanted mode. The oscillations in the wanted mode are, mostoften, especially in the case of application of the measuring transduceras a Coriolis, mass flow meter and/or densimeter, developed, at leastpartially, as lateral bending oscillations and, in the case of mediumflowing through the measuring tubes, as a result of therein inducedCoriolis forces, as additional, equal frequency oscillationssuperimposed in the so-called Coriolis mode. Accordingly, the—here mostoften electrodynamic—exciter mechanism is embodied in such a manner,that, therewith, the two measuring tubes are excitable in the wantedmode, at least partially, especially also predominantly, to oppositeequal bending oscillations differentially—thus through introduction ofexciter forces acting simultaneously along a shared line of action,however, in opposed direction.

For registering vibrations, especially bending oscillations, of themeasuring tubes excited by means of the exciter mechanism and forproducing oscillation signals representing vibrations, the measuringtransducers have, additionally, in each case, a, most often, likewiseelectrodynamic, sensor arrangement reacting to relative movements of themeasuring tubes. Typically, the sensor arrangement is formed by means ofan inlet-side, oscillation sensor registering oscillations of themeasuring tubes differentially—thus only relative movements of themeasuring tubes—as well as by means of an outlet-side, oscillationsensor registering oscillations of the measuring tubes differentially.Each of the oscillation sensors, which are usually constructed equallywith one another, is formed by means of a permanent magnet held on thefirst measuring tube and a cylindrical coil held on the second measuringtube and permeated by the magnetic field of the permanent magnet.

In operation, the above described tube arrangement formed by means ofthe two measuring tubes is excited by means of the electromechanicalexciter mechanism, at least at times, to execute mechanical oscillationsin the wanted mode at at least one dominating, wanted, oscillationfrequency. Selected as oscillation frequency for the oscillations in thewanted mode is, in such case, usually a natural, instantaneous,resonance frequency of the tube arrangement, which, in turn, dependsessentially both on size, shape and material of the measuring tubes aswell as also on an instantaneous density of the medium; in given cases,this wanted oscillation frequency can also be influenced significantlyby an instantaneous viscosity of the medium. As a result of fluctuatingdensity of the medium being measured and/or as a result of media changeoccurring during operation, the wanted oscillation frequency duringoperation of the measuring transducer varies naturally, at least withina calibrated and, thus, predetermined, wanted frequency band, whichcorrespondingly has a predetermined lower, and a predetermined upper,limit frequency.

For defining a wanted oscillatory length of the measuring tubes and,associated therewith, for adjusting the band of the wanted frequency,measuring transducers of the above described type include—additionally,most often, at least one inlet-side, coupling element, which is affixedto both measuring tubes and spaced from the two flow dividers, forforming inlet-side, oscillation nodes for opposite equal vibrations,especially bending oscillations, of both measuring tubes, as well as atleast one outlet-side, coupling element, which is affixed to bothmeasuring tubes and spaced both from the two flow dividers, as well asalso from the inlet-side, coupling element, for forming outlet-side,oscillation nodes for opposite equal vibrations, especially bendingoscillations, of the measuring tubes. In the case of curved measuringtubes, in such case, the length of a section of a deflection curve ofany of the measuring tubes extending between the inlet side and theoutlet-side coupling elements, consequently the length of an imaginarycenter line of the said measuring tube connecting the areal centers ofgravity of all imaginary cross sectional areas of the respectivemeasuring tube, corresponds to the wanted oscillatory length of themeasuring tubes. By means of the coupling elements, which thus belong tothe tube arrangement, additionally also an oscillation quality factor ofthe tube arrangement, as well as also the sensitivity of the measuringtransducer, in total, can be influenced, in a manner such that, for aminimum required sensitivity of the measuring transducer, at least oneminimum, wanted oscillatory length is provided.

Development in the field of measuring transducers of vibration-type has,in the meantime, reached a level, wherein modern measuring transducersof the described type can, for a broad application spectrum of flowmeasurement technology, satisfy highest requirements as regardsprecision and reproducibility of the measurement results. Thus, suchmeasuring transducers are, in practice, applied for mass flow rates fromsome few l/h (gram per hour) up to some t/min (tons per minute), atpressures of up to 100 bar for liquids or even over 300 bar for gases.The accuracy of measurement achieved, in such case, lies usually atabout 99.9% of the actual value, or above, or at a measuring error ofabout 0.1%, wherein a lower limit of the guaranteed measurement rangecan lie quite easily at about 1% of the measurement range end value. Dueto the high bandwidth of their opportunities for use, industrial grademeasuring transducers of vibration-type are available with nominaldiameters (corresponding to the caliber of the pipeline to be connectedto the measuring transducer, or to the caliber of the measuringtransducer measured at the connecting flange), which lie in a nominaldiameter range between 1 mm and 250 mm and at maximum nominal mass flowrate of 1000 t/h, in each case, for pressure losses of less than 3 bar.A caliber of the measuring tubes lies, in such case, for instance, in arange between 80 mm and 100 mm.

In spite of the fact that, in the meantime, measuring transducers foruse in pipelines with very high mass flow rates and, associatedtherewith, very large calibers of far beyond 100 mm have becomeavailable, there is still considerable interest in obtaining measuringtransducers of high precision and low pressure loss also for yet largerpipeline calibers, about 300 mm or more, or mass flow rates of 1500 t/hor more, for instance for applications in the petrochemical industry orin the field of transport and transfer of petroleum, natural gas, fuels,etc. This leads, in the case of correspondingly scaled enlarging of thealready established measuring transducer designs known from the state ofthe art, especially from EP-A 1 001 254, EP-A 553 939, U.S. Pat. No.4,793,191, US-A 2002/0157479, US-A 2007/0151368, U.S. Pat. No.5,370,002, U.S. Pat. No. 5,796,011, U.S. Pat. No. 6,308,580, U.S. Pat.No. 6,711,958, U.S. Pat. No. 7,134,347, U.S. Pat. No. 7,350,421, or WO-A03/027616, to the fact that the geometric dimensions would beexorbitantly large, especially the installed length corresponding to adistance between the sealing surfaces of both flanges and, in the caseof curved measuring tubes, a maximum lateral extension of the measuringtransducer, especially dimensions for the desired oscillationcharacteristics, the required load bearing ability, as well as themaximum allowed pressure loss. Along with that, also the empty mass ofthe measuring transducer increases unavoidably, with conventionalmeasuring transducers of large nominal diameter already having an emptymass of about 400 kg. Investigations, which have been carried out formeasuring transducers with two bent measuring tubes, constructed, forinstance, according to U.S. Pat. No. 7,350,421 or U.S. Pat. No.5,796,011, as regards their to-scale enlargement to still greaternominal diameters, have, for example, shown that, for nominal diametersof more than 300 mm, the empty mass of a to-scale enlarged, conventionalmeasuring transducer would lie far above 500 kg, accompanied by aninstalled length of more than 3000 mm and a maximum lateral extension ofmore than 1000 mm. As a result, it can be said that industrial grade,mass producible, measuring transducers of conventional design andmaterials with nominal diameters far above 300 mm cannot be expected inthe foreseeable future both for reasons of technical implementability,as well as also due to economic considerations.

Proceeding from the above recounted state of the art, it is consequentlyan object of the invention to provide a measuring transducer of highsensitivity and high oscillation quality factor, which also in the caseof large mass flow rates of more than 1000 t/h, causes only a smallpressure loss of, as much as possible, less than 3 bar and which alsohas a construction, which is as compact as possible at large nominaldiameters of over 100 mm and, not last, is also suitable forapplications involving extremely hot, or extremely cold, media and/orsignificant fluctuating media temperatures.

For achieving the object, the invention resides in a measuringtransducer of vibration-type for registering at least one physical,measured variable of a flowable medium guided in a pipeline, forexample, a gas, a liquid, a powder or other flowable material, and/orfor producing Coriolis forces serving for registering a mass flow rateof a flowable medium guided in a pipeline, especially a gas, a liquid, apowder or other flowable material. The measuring transducer comprises,according to the invention, a, for example, at least partiallyessentially tubular and/or at least partially externally circularlycylindrical, transducer housing, of which an inlet-side, first housingend is formed by means of an inlet-side, first flow divider havingexactly four, for example, circularly cylindrical, tapered or conical,flow openings spaced, in each case, from one another, and anoutlet-side, second housing end is formed by means of an outlet-side,second flow divider having exactly four, for example, circularlycylindrical, tapered or conical, flow openings spaced, in each case,from one another. Furthermore, the measuring transducer comprises a tubearrangement with exactly four, curved or bent (for example, at leastsectionally V-shaped and/or at least sectionally circular arc shaped),measuring tubes forming flow paths arranged for parallel flow andconnected to the, for example, equally constructed, flow dividers forguiding flowing medium, especially measuring tubes held oscillatably inthe transducer housing only by means of said flow dividers and/orequally constructed and/or pairwise parallel relative to one another. Ofthe four measuring tubes, for example, measuring tubes constructedequally both as regards geometry as well as also as regards material, afirst measuring tube, especially a circularly cylindrical, firstmeasuring tube, opens with an inlet-side, first measuring tube end intoa first flow opening of the first flow divider and with an outlet-side,second measuring tube end into a first flow opening of the second flowdivider, a second measuring tube, which is at least sectionally parallelto the first measuring tube, opens with an inlet-side, first measuringtube end into a second flow opening of the first flow divider and withan outlet-side, second measuring tube end into a second flow opening ofthe second flow divider, a third measuring tube opens with aninlet-side, first measuring tube end into a third flow opening of thefirst flow divider and with an outlet-side, second measuring tube endinto a third flow opening of the second flow divider, as well as afourth measuring tube, which is at least sectionally parallel to thethird measuring tube, opens with an inlet-side, first measuring tube endinto a fourth flow opening of the first flow divider and with anoutlet-side, second measuring tube end into a fourth flow opening of thesecond flow divider. Additionally, the measuring transducer comprises anelectromechanical exciter mechanism, for example, one formed by means ofone or more electrodynamic oscillation exciters, for producing and/ormaintaining mechanical oscillations, especially bending oscillations, ofthe four measuring tubes. In the case of the measuring transducer of theinvention, the measuring tubes are so embodied and arranged in themeasuring transducer, that the tube arrangement has lying between thefirst imaginary longitudinal section plane and the second imaginarylongitudinal section plane of the measuring transducer, and parallel tothe first imaginary longitudinal section plane of the measuringtransducer and to the second imaginary longitudinal section plane of themeasuring transducer, a first imaginary longitudinal section plane, withrespect to which the tube arrangement is mirror symmetric, and the tubearrangement has perpendicular to its imaginary first longitudinalsection plane a second imaginary longitudinal section plane, withrespect to which the tube arrangement is likewise mirror symmetric.

Moreover, the invention resides in a measuring system for measuringdensity and/or mass flow rate, for example, thus a total mass flowtotalled over a time interval, of a medium flowing, at least at times,in a pipeline, for example, with a mass flow rate of more than 1000 t/h,for instance, a medium such as a gaseous, a liquid, a powder or otherflowable material. The measuring system, for example, one embodied as anin-line measuring device and/or a measuring device in compactconstruction, comprises said measuring transducer, as well as,electrically coupled with the measuring transducer, for example,arranged in an electronics housing mechanically connected with thetransducer housing, a transmitter-electronics for activating themeasuring transducer, especially its exciter mechanism, and forevaluating oscillation signals delivered by the measuring transducer.Especially, the invention resides thus in the use of said measuringsystem for measuring a density and/or a mass flow rate, especially atotal mass flow totalled over a time interval, and/or a viscosity and/ora Reynolds number of a medium flowing in a process line, for instance, apipeline, at least at times, with a mass flow rate of more than 1000t/h, for example, more than 1500 t/h, for instance, a medium such ase.g. a gaseous, a liquid, a powder or other flowable material.

According to a first embodiment of the measuring transducer of theinvention, the exciter mechanism is embodied in such a manner that,therewith, each of the four measuring tubes is excitable, for example,even simultaneously, to bending oscillations.

According to a second embodiment of the measuring transducer of theinvention, the exciter mechanism is embodied in such a manner that thefirst measuring tube and the second measuring tube are excitable tobending oscillations, which are opposite equal relative to the secondimaginary longitudinal section planar, for example, thus symmetricrelative to the second imaginary longitudinal section plane, and thethird measuring tube and the fourth measuring tube to bendingoscillations, which are opposite equal relative to the second imaginarylongitudinal section plane, for example, thus symmetric relative to thesecond imaginary longitudinal section plane.

According to a third embodiment of the measuring transducer of theinvention, the exciter mechanism is embodied in such a manner that thefirst measuring tube and the third measuring tube are excitable tobending oscillations, which are opposite equal relative to the secondimaginary longitudinal section plane, for example, thus symmetricrelative to the second imaginary longitudinal section plane, and thesecond measuring tube and the fourth measuring tube to bendingoscillations, which are opposite equal relative to the second imaginarylongitudinal section plane, for example, thus symmetric relative to thesecond imaginary longitudinal section plane.

According to a fourth embodiment of the measuring transducer of theinvention, the exciter mechanism is embodied in such a manner that anatural bending oscillation mode of first type inherent to the tubearrangement is excitable, in which bending oscillation mode of firsttype the first measuring tube and the second measuring tube execute,relative to the second imaginary longitudinal section plane, oppositeequal, for example, thus relative to the second imaginary longitudinalsection plane, symmetric, bending oscillations about, in each case, astatic rest position associated with the respective measuring tube, forinstance, cantilever, bending oscillations about, in each case, animaginary oscillation axis parallel to at least two of the imaginaryconnecting axes, and in which bending oscillation mode of first type thethird measuring tube and the fourth measuring tube execute, relative tothe second imaginary longitudinal section plane, opposite equal, forexample, thus, relative to the second imaginary longitudinal sectionplane, symmetric, bending oscillations about, in each case, a staticrest position associated with the respective measuring tube, forinstance, cantilever, bending oscillations about, in each case, animaginary oscillation axis parallel to at least two of the imaginaryconnecting axes, in such a manner, that, relative to the secondimaginary longitudinal section plane, said bending oscillations of thefirst measuring tube are thus opposite equal to said bendingoscillations of the third measuring tube, and that, relative to thesecond imaginary longitudinal section plane, said bending oscillationsof the second measuring tube are thus opposite equal to said bendingoscillations of the fourth measuring tube.

Developing this embodiment of the invention further, the excitermechanism is embodied in such a manner that a natural bendingoscillation mode of second type inherent to the tube arrangement isexcitable, for example, thus simultaneously with the bending oscillationmode of first type, in which bending oscillation mode of second type thefirst measuring tube and the second measuring tube execute, relative tothe second imaginary longitudinal section plane, opposite equal, forexample, thus relative to the second imaginary longitudinal sectionplane, symmetric, bending oscillations about, in each case, a staticrest position associated with the respective measuring tube, forinstance, cantilever, bending oscillations about, in each case, animaginary oscillation axis parallel to at least two of the imaginaryconnecting axes, and in which bending oscillation mode of second typethe third measuring tube and the fourth measuring tube execute, relativeto the second imaginary longitudinal section plane, opposite equal, forexample, thus relative to the second imaginary longitudinal sectionplane, symmetric, bending oscillations about, in each case, a staticrest position associated with the respective measuring tube, forinstance, cantilever, bending oscillations about, in each case, animaginary oscillation axis parallel to at least two of the imaginaryconnecting axes, in such a manner, that, relative to the secondimaginary longitudinal section plane, said bending oscillations of thefirst measuring tube are thus opposite equal to said bendingoscillations of the fourth measuring tube, and that, relative to thesecond imaginary longitudinal section plane, said bending oscillationsof the second measuring tube are thus opposite equal to said bendingoscillations of the third measuring tube.

Alternatively, or in supplementation, it is additionally provided thatan eigenfrequency of the bending oscillation mode of first type, forexample, such an eigenfrequency measurable in the case of a tubearrangement completely filled with water, is different, for example, bymore than 10 Hz, from an eigenfrequency of the bending oscillation modeof second type, for example, such an eigenfrequency in the case of atube arrangement completely filled with water and/or measurable at thesame time as the eigenfrequency of the bending oscillation mode of firsttype; e.g. in such a manner, that said eigenfrequency of the bendingoscillation mode of first type is greater by more than 10 Hz than saideigenfrequency of the bending oscillation mode of second type or thatsaid eigenfrequency of the bending oscillation mode of first type issmaller by more than 10 Hz than said eigenfrequency of the bendingoscillation mode of second type.

According to a fifth embodiment of the invention, each of the fourmeasuring tubes has a measuring tube peak, defined as the greatestperpendicular distance of the respective measuring tube from the firstimaginary longitudinal section plane.

According to a sixth embodiment of the measuring transducer theinvention lies a center of mass the tube arrangement in a both to thefirst imaginary longitudinal section plane as well as also to the secondimaginary longitudinal section plane, in each case, perpendicularimaginary cross sectional planar the tube arrangement.

According to a seventh embodiment of the measuring transducer of theinvention, the tube arrangement is mirror symmetric relative to animaginary cross sectional plane the tube arrangement perpendicular bothto the first imaginary longitudinal section plane as well as also to thesecond imaginary longitudinal section plane.

According to an eighth embodiment of the measuring transducer of theinvention, each of the four measuring tubes has a measuring tube peak,defined as the greatest perpendicular distance of the respectivemeasuring tube from the first imaginary longitudinal section plane, andan imaginary cross sectional plane of the tube arrangement perpendicularto both the first imaginary longitudinal section plane as well as alsothe second imaginary longitudinal section plane intersects each of thefour measuring tubes in its respective measuring tube peak.

According to a ninth embodiment of the measuring transducer of theinvention, a middle segment of the transducer housing at least partiallyis formed by means of a straight, for example, circularly cylindrical,support tube, for instance, in such a manner, that a segment of thefirst measuring tube extending outwards from said support tube on afirst side and a segment of the second measuring tube extending outwardsfrom said support tube on the first side are surrounded by a firsthousing cap of the transducer housing, and that a segment of the thirdmeasuring tube extending outwards from said support tube on a secondside lying opposite to the first side and a segment of the fourthmeasuring tube extending outwards from said support tube on the secondside are surrounded by a second housing cap of the transducer housing,for example, a second housing cap constructed equally to the firsthousing cap.

According to a tenth embodiment of the measuring transducer of theinvention, it is additionally provided, that the two flow dividers areadditionally so embodied and arranged in the measuring transducer, thatan imaginary first connecting axis of the measuring transducerimaginarily connecting the first flow opening of the first flow dividerwith the first flow opening of the second flow divider extends parallelto an imaginary second connecting axis of the measuring transducerimaginarily connecting the second flow opening of the first flow dividerwith the second flow opening of the second flow divider, that animaginary third connecting axis of the measuring transducer imaginarilyconnecting the third flow opening of the first flow divider with thethird flow opening of the second flow divider extends parallel to animaginary fourth connecting axis of the measuring transducer imaginarilyconnecting the fourth flow opening of the first flow divider with thefourth flow opening of the second flow divider. Developing thisembodiment of the invention further, it is additionally provided, that afirst imaginary longitudinal section plane of the measuring transducer,within which the first imaginary connecting axis and the secondimaginary connecting axis extend, for example, parallel to a principalflow axis of the measuring transducer aligning with the pipeline isparallel to a second imaginary longitudinal section plane of themeasuring transducer, within which the imaginary third connecting axisand the imaginary fourth connecting axis extend, for example, in such amanner, that the first imaginary longitudinal section plane of the tubearrangement lies between the first and second imaginary longitudinalsection planes of the measuring transducer and/or is parallel to thefirst and second imaginary longitudinal section planes of the measuringtransducer.

According to an eleventh embodiment of the measuring transducer of theinvention, it is additionally provided, that the two flow dividers areso embodied and arranged in the measuring transducer, that a thirdimaginary longitudinal section plane of the measuring transducer, withinwhich the imaginary first connecting axis and the imaginary thirdconnecting axis extend, is parallel to a fourth imaginary longitudinalsection plane of the measuring transducer, within which the imaginarysecond connecting axis and the imaginary fourth connecting axis extend.Developing this embodiment of the invention further, it is additionallyprovided, that the second imaginary longitudinal section plane of thetube arrangement extends between the third imaginary longitudinalsection plane of the measuring transducer and the fourth imaginarylongitudinal section plane of the measuring transducer, for example, insuch a manner, that the second imaginary longitudinal section plane ofthe tube arrangement is parallel to the third imaginary longitudinalsection plane of the measuring transducer and parallel to the fourthimaginary longitudinal section plane of the measuring transducer.

According to a twelfth embodiment of the measuring transducer of theinvention, it is additionally provided, that the four flow openings ofthe first flow divider are so arranged, that imaginary areal centers ofgravity associated with cross sectional areas, especially circularlyshaped, cross sectional areas, of the flow openings of the first flowdivider form the vertices of an imaginary rectangle or of an imaginarysquare, wherein said cross sectional areas lie in a shared imaginarycross sectional cutting plane of the first flow divider, for example,perpendicular to the first imaginary longitudinal section plane of themeasuring transducer, or to the second imaginary longitudinal sectionplane of the measuring transducer.

According to a thirteenth embodiment of the measuring transducer of theinvention, it is additionally provided, that the four flow openings ofthe second flow divider so are arranged, that imaginary areal centers ofgravity associated with cross sectional areas of the flow openings ofthe second flow divider form the vertices of an imaginary rectangle orof an imaginary square, wherein said cross sectional areas lie in ashared imaginary cross sectional cutting plane of the second flowdivider, for example, perpendicular to the first imaginary longitudinalsection plane of the measuring transducer, or to the second imaginarylongitudinal section plane of the measuring transducer.

According to a fourteenth embodiment of the measuring transducer of theinvention, it is additionally provided, that each of the four measuringtubes, especially equally large measuring tubes, has a caliber, whichamounts to more than 40 mm, especially more than 60 mm. Developing thisembodiment of the invention further, it is additionally provided, thatthe measuring tubes are so bent and so arranged, that a caliber toheight ratio of the tube arrangement, defined by a ratio of the caliberof the first measuring tube to a maximal lateral expanse of the tubearrangement, measured from a peak of the first measuring tube to a peakof the third measuring tube, amounts to more than 0.05, especially morethan 0.07 and/or less than 0.35, especially less than 0.2.

According to a fifteenth embodiment of the measuring transducer of theinvention, it is additionally provided, that the first flow divider hasa flange, especially a flange having mass of more than 50 kg, forconnecting the measuring transducer to a tubular segment of the pipelineserving for supplying medium to the measuring transducer and the secondflow divider has a flange, especially a flange having a mass of morethan 50 kg, for connecting the measuring transducer to a segment of thepipeline serving for removing medium from the measuring transducer.Developing this embodiment of the invention further, each of the flangeshas a sealing surface for fluid tight connecting of the measuringtransducer with the, in each case, corresponding tubular segment of thepipeline, wherein a distance between the sealing surfaces of bothflanges defines an installed length of the measuring transducer,especially an installed length amounting to more than 1000 mm and/orless than 3000 mm. Especially, the measuring transducer is additionallyso embodied, that, in such case, a measuring tube length of the firstmeasuring tube corresponding to a length of a section of the deflectioncurve of the first measuring tube extending between the first flowopening of the first flow divider and the first flow opening of thesecond flow divider is so selected, that a measuring tube length toinstalled length ratio of the measuring transducer, as defined by aratio of the measuring tube length of the first measuring tube to theinstalled length of the measuring transducer, amounts to more than 0.7,especially more than 0.8 and/or less than 1.2, and/or that a caliber toinstalled length ratio of the measuring transducer, as defined by aratio of a caliber of the first measuring tube to the installed lengthof the measuring transducer, amounts to more than 0.02, especially morethan 0.05 and/or less than 0.09. Alternatively thereto or insupplementation thereof, the measuring transducer is so embodied, that anominal diameter to installed length ratio of the measuring transducer,as defined by a ratio of the nominal diameter of the measuringtransducer to the installed length of the measuring transducer, issmaller than 0.3, especially smaller than 0.2 and/or greater than 0.1,wherein the nominal diameter corresponds to a caliber of the pipeline,in whose course the measuring transducer is to be used.

In a sixteenth embodiment of the measuring transducer of the invention,it is additionally provided, that a measuring tube length of the firstmeasuring tube corresponding to a length of a section of the deflectioncurve of the first measuring tube extending between the first flowopening of the first flow divider and the first flow opening of thesecond flow divider amounts to more than 1000 mm, especially more than1200 mm and/or less than 3000 mm, especially less than 2500.

In a seventeenth embodiment of the measuring transducer of theinvention, it is additionally provided, that each of the four measuringtubes, for example, four measuring tubes of equal caliber, is soarranged, that a smallest lateral separation of each of the fourmeasuring tubes, for example, measuring tubes of equal length, from ahousing side wall of the transducer housing is, in each case, greaterthan zero, for example, also greater than 3 mm and/or greater than twicea respective tube wall thickness; and/or that a smallest lateralseparation between two neighboring measuring tubes amounts to, in eachcase, greater than 3 mm and/or greater than the sum of their respectivetube wall thicknesses.

In an eighteenth embodiment of the measuring transducer of theinvention, it is additionally provided, that each of the flow openingsis so arranged, that a smallest lateral separation of each of the flowopenings from a housing side wall of the transducer housing amounts, ineach case, to greater than zero, for example, also greater than 3 mmand/or greater than twice a smallest tube wall thickness of themeasuring tubes; and/or that a smallest lateral separation between theflow openings amounts to greater than 3 mm and/or greater than twice asmallest tube wall thickness of the measuring tubes.

According to a nineteenth embodiment of the measuring transducer of theinvention, it is additionally provided, that the exciter mechanism isembodied in such a manner, that the first measuring tube and the secondmeasuring tube are excitable during operation to opposite equal bendingoscillations and the third measuring tube and the fourth measuring tubeare excitable during operation to opposite equal bending oscillations.

In a twentieth embodiment of the measuring transducer of the invention,it is additionally provided, that a mass ratio of an empty mass of thetotal measuring transducer to an empty mass of the first measuring tubeis greater than 10, especially greater than 15 and smaller than 25.

In a twenty-first embodiment of the measuring transducer of theinvention, it is additionally provided, that an empty mass, M₁₈, of thefirst measuring tube, especially each of the measuring tubes, is greaterthan 20 kg, especially greater than 30 kg and/or smaller than 50 kg.

According to a twenty-second embodiment of the measuring transducer ofthe invention, it is additionally provided, that an empty mass of themeasuring transducer is greater than 200 kg, especially greater than 300kg.

In a twenty-third embodiment of the measuring transducer of theinvention, it is additionally provided, that a nominal diameter of themeasuring transducer, which corresponds to a caliber of the pipeline, inwhose course the measuring transducer is to be used, amounts to morethan 100 mm, especially greater than 300 mm. In advantageous manner, themeasuring transducer is additionally so embodied, that a mass to nominaldiameter ratio of the measuring transducer, as defined by a ratio of theempty mass of the measuring transducer to the nominal diameter of themeasuring transducer, is smaller than 2 kg/mm, especially smaller than 1kg/mm and/or greater than 0.5 kg/mm.

In a twenty-fourth embodiment of the measuring transducer of theinvention, it is additionally provided, that the first and the secondmeasuring tubes are of equal construction, at least as regards amaterial, of which their tube walls are, in each case, composed, and/oras regards their geometrical tube dimensions, especially a tube length,a tube wall thickness, a tube outer diameter and/or a caliber.

According to a twenty-fifth embodiment of the invention, it isadditionally provided, that the third and fourth measuring tubes are ofequal construction, at least as regards a material, of which their tubewalls are, in each case, composed, and/or as regards their geometrictube dimensions, especially a tube length, a tube wall thickness, a tubeouter diameter and/or a caliber.

According to a twenty-sixth embodiment of the measuring transducer ofthe invention, it is additionally provided, that all four measuringtubes are of equal construction, as regards a material, of which theirtube walls are composed, and/or as regards their geometric tubedimensions, especially a tube length, a tube wall thickness, a tubeouter diameter and/or a caliber.

In a twenty-seventh embodiment of the measuring transducer of theinvention, it is additionally provided, that a material, of which thetube walls of the four measuring tubes are at least partially composed,is titanium and/or zirconium and/or, for example, stainless and/or highstrength steel, duplex steel and/or super duplex steel, or Hastelloy.

In a twenty-eighth embodiment of the measuring transducer of theinvention, it is additionally provided, that the transducer housing, theflow dividers and tube walls of the measuring tubes are, in each case,composed of steel, for example, stainless steel.

In a twenty-ninth embodiment of the measuring transducer of theinvention, it is additionally provided, that the exciter mechanism isformed by means of a first oscillation exciter, especially anelectrodynamic, first oscillation exciter and/or a first oscillationexciter differentially exciting oscillations of the first measuring tuberelative to the second measuring tube. Especially, the exciter mechanismis formed by means of a second oscillation exciter, for example, anelectrodynamic second oscillation exciter and/or a second oscillationexciter differentially exciting oscillations of the third measuring tuberelative to the fourth measuring tube. In such case, it is additionallyprovided, that the first and second oscillation exciters areinterconnected electrically in series, in such a manner, that a combineddriver signal excites combined oscillations of the first and thirdmeasuring tubes relative to the second and fourth measuring tube. Theoscillation exciter of the exciter mechanism can be formed, for example,by means of a permanent magnet held on the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held on the second measuring tube, and wherein the secondoscillation exciter is formed by means of a permanent magnet held on thethird measuring tube and a cylindrical coil permeated by the magneticfield of the permanent magnet and held on the fourth measuring tube.

According to a first further development of the measuring transducer ofthe invention, such further comprises: A first coupling element of firsttype, which is spaced both from the first flow dividers as well as alsofrom the second flow dividers, affixed on the inlet side to each of thefour measuring tubes and having, for example, an H- or X-shaped basicshape, for tuning eigenfrequencies of natural oscillation modes of thetube arrangement, for example, bending oscillation modes, as well as asecond coupling element of first type, which is spaced both from thefirst flow dividers as well as also from the second flow dividers,affixed on the outlet side to each of the four measuring tubes, having,for example, an H- or X-shaped basic shape and/or essentially equallyconstructed to the first coupling element of first type, for tuningeigenfrequencies of natural oscillation modes of the tube arrangement,for example, bending oscillation modes.

According to a first embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thateach of the two coupling elements of first type is symmetric relative tothe first imaginary longitudinal section plane of the tube arrangement.

According to a second embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thateach of the two coupling elements of first type is symmetric relative tothe second imaginary longitudinal section plane of the tube arrangement.

According to a third embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thatboth coupling elements of first type are arranged in the measuringtransducer symmetrically relative to an imaginary cross sectional planeof the tube arrangement perpendicular both to the first imaginarylongitudinal section plane as well as also to the second imaginarylongitudinal section plane of the tube arrangement.

According to a fourth embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thatthe two coupling elements of first type are arranged in the measuringtransducer equidistantly relative to an imaginary cross sectional planeof the tube arrangement perpendicular both to the first imaginarylongitudinal section plane as well as also to the second imaginarylongitudinal section plane of the tube arrangement.

According to a fifth embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thatthe two coupling elements of first type are arranged extending parallelin the measuring transducer relative to an imaginary cross sectionalplane of the tube arrangement perpendicular both to the first imaginarylongitudinal section plane as well as also to the second imaginarylongitudinal section plane of the tube arrangement.

According to a sixth embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thateach of the two coupling elements of first type is so embodied andplaced in the measuring transducer that it is symmetric relative to thefirst imaginary longitudinal section plane of the tube arrangementand/or relative to the second imaginary longitudinal section plane ofthe tube arrangement.

According to a seventh embodiment of the first further development ofthe measuring transducer of the invention, it is additionally providedthat each of the two coupling elements of first type is so embodied andplaced in the measuring transducer that it is embodied X-shaped asprojected onto an imaginary cross sectional plane of the tubearrangement perpendicular both to the first imaginary longitudinalsection plane of the tube arrangement as well as also to the secondimaginary longitudinal section plane of the tube arrangement, or that itis embodied H-shaped as projected onto an imaginary cross sectionalplane of the tube arrangement perpendicular to the first imaginarylongitudinal section plane and the second imaginary longitudinal sectionplane of the tube arrangement.

According to an eighth embodiment of the first further development ofthe measuring transducer of the invention, it is additionally providedthat both the first coupling element of first type as well as also thesecond coupling element of first type are formed by means of plateshaped elements.

According to a ninth embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thateach of the two coupling elements of first type is at least sectionallybulged, for example, in such a manner, that it is at least sectionallyconvex relative to an imaginary cross sectional plane of the tubearrangement extending between the first coupling element of first typeand the second coupling element of first type and perpendicular both tothe first imaginary longitudinal section plane of the tube arrangementas well as also to the second imaginary longitudinal section plane ofthe tube arrangement.

According to a tenth embodiment of the first further development of themeasuring transducer of the invention, it is additionally provided thatboth the first coupling element of first type as well as also the secondcoupling element of first type are at least sectionally convex relativeto, namely as seen from, an imaginary cross sectional plane of the tubearrangement extending between the first coupling element of first typeand the second coupling element of first type and perpendicular both tothe first imaginary longitudinal section plane of the tube arrangementas well as also to the second imaginary longitudinal section plane ofthe tube arrangement.

According to an eleventh embodiment of the first further development ofthe measuring transducer of the invention, such further comprises: A,for example, plate shaped, first coupling element of second type, which,for forming inlet-side oscillation nodes both for vibrations, forexample bending oscillations, of the first measuring tube as well asalso for thereto opposite equal vibrations, for example bendingoscillations, of the second measuring tube is affixed on the inlet sideto the first measuring tube and to the second measuring tube, forexample, both to a tube segment of the first measuring tube extendingbetween the first flow dividers and the first coupling element of firsttype as well as also to a tube segment of the second measuring tubeextending between the first flow dividers and the first coupling elementof first type; a, for example, plate shaped and/or equally constructedto the first coupling element of second type and/or parallel to thefirst coupling element of second type, second coupling element of secondtype, which for forming outlet-side oscillation nodes both forvibrations, for example bending oscillations, of the first measuringtube as well as also for thereto opposite equal vibrations, for examplebending oscillations, of the second measuring tube, is affixed on theoutlet side to the first measuring tube and to the second measuringtube, for example, both to a tube segment of the first measuring tubeextending between the second flow dividers and the second couplingelement of first type as well as also to a tube segment of the secondmeasuring tube extending between the second flow dividers and the secondcoupling element of first type; a, for example, plate shaped and/orequally constructed to the first coupling element of second type and/orparallel to the second coupling element of second type, third couplingelement of second type, which, for forming inlet-side oscillation nodesboth for vibrations, for example bending oscillations, of the thirdmeasuring tube as well as also thereto opposite equal vibrations, forexample bending oscillations, of the fourth measuring tube, is affixed,spaced both from the first flow dividers as well as also from the secondflow dividers on the inlet side, to the third measuring tube and to thefourth measuring tube, for example, both to a tube segment of the thirdmeasuring tube extending between the first flow dividers and the firstcoupling element of first type as well as also to a tube segment of thefourth measuring tube extending between the first flow dividers and thefirst coupling element of first type; as well as a, for example, plateshaped and/or equally constructed to the first coupling element ofsecond type and/or parallel to the first coupling element of secondtype, fourth coupling element of second type, which, for the formingoutlet-side oscillation nodes both for vibrations, for example bendingoscillations, of the third measuring tube as well as also for theretoopposite equal vibrations, for example bending oscillations, of thefourth measuring tube is affixed on the outlet side, spaced both fromthe first flow dividers as well as also from the second flow dividers,as well as also from the first coupling element, to the third measuringtube and to the fourth measuring tube, for example, both to a tubesegment of the third measuring tube extending between the second flowdividers and the second coupling element of first type as well as alsoto a tube segment of the fourth measuring tube extending between thesecond flow dividers and the second coupling element of first type. Themeasuring transducer according to this embodiment of the invention canbe manufactured, for example, by first affixing both the first couplingelement of second type as well as also the second coupling element ofsecond type, in each case, to the first measuring tube and to the secondmeasuring tube for the manufacture of a first measuring tube package aswell as both the third coupling element of second type as well as alsothe fourth coupling element of second type, in each case, to the thirdmeasuring tube and to the fourth measuring tube for the manufacture of asecond measuring tube package; and that thereafter first affixing boththe first coupling element of first type as well as also the secondcoupling element of first type, in each case, to at least one, forexample, also each, of the measuring tubes of the first measuring tubepackage and to at least one, for example, also each, of the measuringtubes of the second measuring tube package.

In a second further development of the invention, the measuringtransducer additionally comprises a sensor arrangement for producingoscillation signals representing vibrations, especially bendingoscillations, of the measuring tubes, by reacting to vibrations of themeasuring tubes, especially bending oscillations excited by means of theexciter mechanism. The sensor arrangement is, for example, anelectrodynamic sensor arrangement and/or is formed by means ofoscillation sensors constructed equally to one another.

In a first embodiment of the second further development of theinvention, it is provided, that the sensor arrangement is formed bymeans of an inlet-side, first oscillation sensor, especially anelectrodynamic, first oscillation sensor and/or a first oscillationsensor differentially registering oscillations of the first measuringtube relative to the second measuring tube, as well as by means of anoutlet-side, second oscillation sensor, especially an electrodynamic,second oscillation sensor and/or a second oscillation sensordifferentially registering oscillations of the first measuring tuberelative to the second measuring tube, especially in such a manner thata measuring length of the measuring transducer corresponding to a lengthof a section of a deflection curve of the first measuring tube extendingbetween the first oscillation sensor and the second oscillation sensoramounts to more than 500 mm, especially more than 600 mm and/or lessthan 1200 mm, and/or in such a manner that a caliber to measuring lengthratio of the measuring transducer, as defined by a ratio of a caliber ofthe first measuring tube to the measuring length of the measuringtransducer, amounts to more than 0.05, especially more than 0.09.Additionally, the first oscillation sensor can be formed by means of apermanent magnet held on the first measuring tube and a cylindrical coilpermeated by the magnetic field of the permanent magnet and held on thesecond measuring tube, and the second oscillation sensor by means of apermanent magnet held on the first measuring tube and a cylindrical coilpermeated by the magnetic field of the permanent magnet and held on thesecond measuring tube.

In a second embodiment of the second further development of theinvention, it is additionally provided, that the sensor arrangement isformed by means of an inlet-side, first oscillation sensor, especiallyan electrodynamic, first oscillation sensor and/or a first oscillationsensor differentially registering oscillations of the first measuringtube relative to the second measuring tube, by an outlet-side, secondoscillation sensor, especially an electrodynamic, second oscillationsensor and/or a second oscillation sensor differentially registeringoscillations of the first measuring tube relative to the secondmeasuring tube, by an inlet-side, third oscillation sensor, especiallyan electrodynamic, third oscillation sensor and/or a third oscillationsensor differentially registering oscillations of the third measuringtube relative to the fourth measuring tube, as well as by anoutlet-side, fourth oscillation sensor, especially an electrodynamic,fourth oscillation sensor and/or a fourth oscillation sensordifferentially registering oscillations of the third measuring tuberelative to the fourth measuring tube, especially in such a manner, thata measuring length of the measuring transducer corresponding to asection of a deflection curve of the first measuring tube extendingbetween the first oscillation sensor and the second oscillation sensoramounts to more than 500 mm, especially more than 600 mm and/or lessthan 1200 mm, and/or in such a manner that a caliber to measuring lengthratio of the measuring transducer, as defined by a ratio of a caliber ofthe first measuring tube to the measuring length of the measuringtransducer, amounts to more than 0.05, especially more than 0.09. Insuch case, in advantageous manner, the first and third oscillationsensors can be interconnected electrically in series in such a manner,that a combined oscillation signal represents combined inlet-sideoscillations of the first and third measuring tubes relative to thesecond and fourth measuring tube, and/or the second and fourthoscillation sensors can be interconnected electrically in series in sucha manner, that a combined oscillation signal represents combinedoutlet-side oscillations of the first and third measuring tubes relativeto the second and fourth measuring tube. Alternatively or insupplementation, the first oscillation sensor can further be formed bymeans of a permanent magnet held on the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held on the second measuring tube, and the second oscillation sensorby means of a permanent magnet held on the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held on the second measuring tube, and/or the third oscillationsensor by means of a permanent magnet held on the third measuring tubeand a cylindrical coil permeated by the magnetic field of the permanentmagnet and held on the fourth measuring tube and the fourth oscillationsensor by means of a permanent magnet held on the third measuring tubeand a cylindrical coil permeated by the magnetic field of the permanentmagnet and held on the fourth measuring tube.

According to a first embodiment of the measuring system of theinvention, it is additionally provided that the four measuring tubesduring operation simultaneously execute bending oscillations, excited bythe exciter mechanism, for example, in a bending oscillation fundamentalmode of first type. Developing this embodiment of the invention further,it is additionally provided, that the exciter mechanism effectsoscillations of the measuring tubes, especially bending oscillations inthe first bending oscillation mode of first type by providing that anexciter force generated by means of the first oscillation exciter andacting on the first measuring tube is opposite, for example, alsoopposite equal, to an exciter force generated at the same time by meansof the first oscillation exciter and acting on the second measuringtube.

According to a second embodiment of the measuring system of theinvention, it is additionally provided that the exciter mechanismincludes at least a first oscillation exciter, for example, one actingdifferentially on the first and second measuring tubes, for example,thereto affixed and/or an electro-dynamic, first oscillation exciter,for converting electrical excitation power fed by means of thetransmitter electronics into the exciter mechanism into mechanicalexciter forces, for example, exciter forces having at least one signalfrequency corresponding to an eigenfrequency of a natural mode ofoscillation of the tube arrangement effecting variable and/or periodic,bending oscillations of the first measuring tube and bendingoscillations of the second measuring tube opposite equal to said bendingoscillations of the first measuring tube relative to the secondimaginary longitudinal section plane of the tube arrangement. Developingthis embodiment of the invention further, it is additionally providedthat the first oscillation exciter is formed by means of a permanentmagnet held on the first measuring tube, for example, in the region of ameasuring tube peak, and a cylindrical coil permeated by the magneticfield of the permanent magnet and held on the second measuring tube, forexample, in the region of a measuring tube peak. Alternatively, or insupplementation, the exciter mechanism can also further comprise asecond oscillation exciter, for example, one acting differentially onthe third and fourth measuring tubes, for example, one affixed theretoand/or an electro-dynamic one and/or one constructed equally to thefirst oscillation exciter and/or electrically serially connected withthe first oscillation exciter, for converting electrical excitationpower fed by means of the transmitter electronics into the excitermechanism into mechanical exciter forces, for example, exciter forceshaving at least one signal frequency corresponding to an eigenfrequencyof a natural mode of oscillation of the tube arrangement effectingvariable and/or periodic, bending oscillations of the third measuringtube and bending oscillations of the fourth measuring tube oppositeequal to said bending oscillations of the third measuring tube relativeto the second imaginary longitudinal section plane of the tubearrangement. The second oscillation exciter can, in such case, be formedby means of a permanent magnet held on the third measuring tube, forexample, in the region of a measuring tube peak, and a cylindrical coilpermeated by the magnetic field of the permanent magnet and held on thefourth measuring tube, for example, in the region of a measuring tubepeak.

According to a third embodiment of the measuring system of theinvention, it is additionally provided that the transmitter electronicsfeeds electrical excitation power into the exciter mechanism by means ofat least one electrical driver signal supplied to the exciter mechanism,for example, a driver signal having a variable maximum voltage leveland/or a variable maximum electrical current level, for example, avariable and/or at least at times periodic, driver signal having atleast one signal frequency corresponding to an eigenfrequency of anatural mode of oscillation of the tube arrangement; and that theexciter mechanism converts the electrical excitation power, especiallypower dependent on a voltage level and on an electrical current level ofthe at least one driver signal, at least partially both into bendingoscillations of the first measuring tube and bending oscillations of thesecond measuring tube opposite equal to bending oscillations of thefirst measuring tube relative to the second imaginary longitudinalsection plane of the tube arrangement as well as also into bendingoscillations of the third measuring tube and bending oscillations of thefourth measuring tube opposite equal to bending oscillations of thethird measuring tube relative to the second imaginary longitudinalsection plane of the tube arrangement. Developing this embodiment of theinvention further, it is additionally provided that the at least onedriver signal is fed to the first oscillation exciter, for instance, insuch a manner, that a first exciter current driven by a variable firstexciter voltage provided by means of the first driver signal flowsthrough its cylindrical coil. Alternatively, or in supplementation, theat least one driver signal can have a plurality of signal componentswith signal frequencies different from one another, wherein at least oneof the signal components of the first driver signal, for instance, asignal component dominating as regards signal power, has a signalfrequency corresponding to an eigenfrequency of a natural mode ofoscillation of the tube arrangement, for example, an eigenfrequency ofthe bending oscillation mode of first type, in which each of the fourmeasuring tubes executes bending oscillations.

According to a fourth embodiment of the measuring system of theinvention, it is additionally provided that the transmitter electronics,based on electrical excitation power converted in the exciter mechanism,generates a viscosity measured value representing viscosity of theflowing medium; and/or that the transmitter electronics, based onoscillation signals delivered by the measuring transducer, generates amass flow measured value representing the mass flow rate of the flowingmedium and/or a density measured value representing density of theflowing medium.

A basic idea of the invention is to use, instead of the tubearrangements with two measuring tubes, through which the medium flows inparallel, as usually used in the case of conventional measuringtransducers of large nominal diameter, tube arrangements with four bent,for example V-shaped or circular arc shaped, measuring tubes, throughwhich the medium flows in parallel, and so, on the one hand, to enablean optimal exploitation of the limited offering of space, while, on theother hand, being able to assure an acceptable pressure loss over abroad measuring range, especially also in the case of very high, massflow rates of far over 1000 t/h. Moreover, the effective flow crosssection of the tube arrangement resulting from the total cross sectionof the four measuring tubes can, in comparison to conventional measuringtransducers of equal nominal diameter and equal empty mass having onlytwo measuring tubes, be directly increased by more than 20%.

An advantage of the invention is additionally, among other things, that,through the application of curved measuring tubes, lasting mechanicalstresses, for example, as a result of thermally related expansion of themeasuring tubes or as a result of clamping forces introduced into themeasuring transducer because of the tube arrangement, are largelyprevented within the tube arrangement or at least kept very low and, asa result, the accuracy of measurement, as well as also the structuralintegrity of the measuring transducer, are safely obtained, even in thecase of extremely hot media, or in the case of temperature gradientsstrongly fluctuating within the tube arrangement as a function of time.Moreover, due to the symmetry characteristics of the tube arrangement,also those transverse forces caused by bending oscillations of curvedmeasuring tubes can largely be neutralized, which—as discussed, amongother things, in the initially mentioned EP-A 1 248 084 and U.S. Pat.No. 7,350,421—act essentially perpendicularly to the longitudinalsection planes of the measuring transducer, or its tube arrangement andcan be quite damaging for the accuracy of measurement of measuringtransducers of vibration-type. Additionally, in the case of measuringtransducers of the aforementioned type in comparison to conventionalmeasuring transducers with only one or two bent measuring tubes, anincreased oscillation quality factor of the measuring transducer, as awhole, could be detected, this being especially a result of asignificantly lessened dissipation of oscillatory energy from themeasuring transducer into the pipeline connected thereto, for instance,as a result of actually undesired deformation of the flow dividers.Moreover, oscillations of the measuring tubes of measuring transducersaccording to the present invention also are—in comparison toconventional measuring transducers—influenced to a significantly lesserdegree by pressure jolts and sound.

A further advantage of the measuring transducer of the invention residesadditionally in the fact that predominantly established, structuraldesigns, such as regards materials used, joining technology,manufacturing steps, etc., can be applied, or must only be slightlymodified, whereby also manufacturing costs are, in total, quitecomparable to those of conventional measuring transducers. As a result,a further advantage of the invention is to be found in the fact that,thereby, not only an opportunity is created for implementingcomparatively compact measuring transducers of vibration-type also withlarge nominal diameters of over 150 mm, especially with a nominaldiameter of larger 250 mm, with manageable geometric dimensions andempty dimensions, but, additionally, also, this can be accomplished inan economically sensible manner.

The measuring transducer of the invention is, consequently, especiallysuitable for measuring flowable media guided in a pipeline having acaliber of larger 150 mm, especially of 300 mm or greater. Additionally,the measuring transducer is also suitable for measuring also mass flows,which are, at least at times, greater than 1000 t/h, especially, atleast at times, amounting to more than 1500 t/h, such as can occur e.g.in the case of applications for measuring petroleum, natural gas orother petrochemical materials.

The invention, as well as other advantageous embodiments thereof, willnow be explained in greater detail on the basis of examples ofembodiments presented in the figures of the drawing. Equal parts areprovided in the figures with equal reference characters; when requiredto avoid clutter or when it otherwise appears sensible, alreadymentioned reference characters are omitted in subsequent figures. Otheradvantageous embodiments or further developments, especially alsocombinations of first only individually explained aspects of theinvention, will become evident additionally from the figures of thedrawing, as well as also alone from the dependent claims. In particular,the figures of the drawing show as follows:

FIGS. 1,2 an in-line measuring device serving, for example, as aCoriolis flow/density/viscosity measuring device, in perspective, alsopartially sectioned, side views;

FIGS. 3 a, 3 b shows a projection of the in-line measuring device ofFIG. 1 in two different side views;

FIG. 4 a in perspective, side view, a measuring transducer ofvibration-type having a tube arrangement formed by means of four bentmeasuring tubes and installed in an in-line measuring device of FIG. 1;

FIG. 4 b the tube arrangement of FIG. 4 a in perspective, side view;

FIGS. 5 a,b a projection of the measuring transducer of FIG. 4 a in twodifferent side views;

FIGS. 6 a,b projections of a tube arrangement of FIG. 4 b in twodifferent side views; and

FIGS. 7 a,b schematically, oscillation modes (V-mode; X-mode) of a tubearrangement of FIG. 4 b, in each case in projection onto an imaginarycross sectional plane of said tube arrangement.

FIGS. 1, 2 show, schematically, a measuring system 1, especially ameasuring system embodied as a Coriolis, mass flow, and/or density,measuring device, which serves, especially, for registering a mass flowm of a medium flowing in a pipeline (not shown) and for representingsuch in a mass flow, measured value representing this mass flowinstantaneously. The medium can be practically any flowable material,for example, a powder, a liquid, a gas, a vapor, or the like.Alternatively or in supplementation, the measuring system 1 can, ingiven cases, also be used for measuring a density ρ and/or a viscosity ηof the medium. Especially, the measuring system is provided formeasuring media, such as e.g. petroleum, natural gas or otherpetrochemical materials, which are flowing in a pipeline having acaliber greater than 250 mm, especially a caliber of 300 mm or more.Especially, the measuring system is also provided for measuring flowingmedia of the aforementioned type, which are caused to flow with a massflow rate of greater than 1000 t/h, especially greater than 1500 t/h.

Measuring system 1, shown here in the form of an in-line measuringdevice, namely a measuring device, which can be inserted into the courseof a pipeline, comprises, for such purpose: A measuring transducer 11 ofvibration-type, through which the medium being measured flows, duringoperation; as well as, electrically connected with the measuringtransducer 11, a transmitter electronics 12 (which is here not shown indetail) for operating the measuring transducer and for evaluatingoscillation signals delivered by the measuring transducer. Inadvantageous manner, the transmitter electronics 12, which is formed,for example, by means of one or more microprocessors and/or by means ofone or more digital signal processors, can e.g. be so designed that,during operation of the measuring system 1, it can exchange measuring,and/or other operating, data with a measured value processing unitsuperordinated to it, for example, a programmable logic controller(PLC), a personal computer and/or a work station, via a datatransmission system, for example, a hardwired fieldbus system and/orwirelessly per radio. Furthermore, the transmitter electronics 12 can beso designed, that it can be fed by an external energy supply, forexample, also via the aforementioned fieldbus system. For the case, inwhich the measuring system 1 is provided for coupling to a fieldbus, orother communication, system, the transmitter electronics 12, forexample, also a transmitter electronics, which is programmable on-siteand/or via a communication system, can include, additionally, acorresponding communication interface for data communication, e.g. forsending the measured data to the already mentioned, programmable logiccontroller or a superordinated process control system and/or forreceiving settings data for the measuring system.

FIGS. 4 a, 4 b, 5 a, 5 b, 6 a, 6 b show different representations of anexample of an embodiment for a measuring transducer 11 of vibration-typesuited for the measuring system 1, especially one serving as a Coriolis,mass flow, density and/or viscosity, transducer, which measuringtransducer 11 is applied, during operation, in the course of a pipeline(not shown), through which a medium to be measured, for example, apowdered, liquid, gaseous or vaporous medium, is flowing. The measuringtransducer 11 serves to produce, as already mentioned, in a mediumflowing therethrough, such mechanical reaction forces, especiallyCoriolis forces dependent on the mass flow rate, inertial forcesdependent on density of the medium and/or frictional forces dependent onviscosity of the medium, which react measurably, especially registerablyby sensor, on the measuring transducer. Derived from these reactionforces describing the medium, by means of evaluating methodscorrespondingly implemented in the transmitter electronics in mannerknown to those skilled in the art, e.g. the mass flow rate m (thus, themass flow), and/or the density and/or the viscosity of the medium can bemeasured.

The measuring transducer 11 includes a transducer housing 7 ₁, which is,here, partially essentially tubular, and thus also externally partiallycircularly cylindrical, in which other components of the measuringtransducer 11 serving for registering the at least one measured variableare accommodated to be protected against external, environmentalinfluences, thus dust or water spray or also any other kinds of forcesacting externally on the measuring transducer. An inlet-side, firsthousing end of the transducer housing 7 ₁ is formed by means of aninlet-side, first flow divider 20 ₁ and an outlet-side, second housingend of the transducer housing 7 ₁ is formed by means of outlet-side,second flow divider 20 ₂. Each of the two flow dividers 20 ₁, 20 ₂,which are, in this respect, formed as integral components of thehousing, includes exactly four, for example, circularly cylindrical ortapered or conical, flow openings 20 _(1A), 20 _(1B), 20 _(1C), 20_(1D), or 20 _(2A), 20 _(2B), 20 _(2C), 20 _(2D), each spaced from oneanother and/or each embodied as an inner cone.

Moreover, each of the flow dividers 20 ₁, 20 ₂, for example,manufactured of steel, is provided with a flange 6 ₁, or 6 ₂, forexample, manufactured of steel, for connecting of the measuringtransducer 11 to a tubular segment of the pipeline serving for supplyingmedium to the measuring transducer, or to a tubular segment of suchpipeline serving for removing medium from the measuring transducer. Eachof the two flanges 6 ₁, 6 ₂ has, according to an embodiment of theinvention, a mass of more than 50 kg, especially more than 60 kg and/orless than 100 kg. For leakage free, especially fluid tight, connectingof the measuring transducer with the, in each case, correspondingtubular segment of the pipeline, each of the flanges includesadditionally, in each case, a corresponding, as planar as possible,sealing surface 6 _(1A), or 6 _(2A). A distance between the two sealingsurfaces 6 _(1A), 6 _(2A) of both flanges defines, thus, for practicalpurposes, an installed length, L₁₁, of the measuring transducer 11. Theflanges are dimensioned, especially as regards their inner diameter,their respective sealing surface as well as the flange bores serving foraccommodating corresponding connection bolts, according to the nominaldiameter D₁₁ provided for the measuring transducer 11 as well as thetherefor, in given cases, relevant industrial standards, correspondingto a caliber of the pipeline, in whose course the measuring transduceris to be used.

As a result of the large nominal diameter especially desired for themeasuring transducer, its installed length L₁₁ amounts, according to anembodiment of the invention, to more than 1200 mm. Additionally, it is,however, provided that the installed length of the measuring transducer11 is kept as small as possible, especially smaller than 3000 mm. Theflanges 6 ₂, 6 ₂ can, as well as also directly evident from FIG. 4 a andsuch as quite usual in the case of such measuring transducers, bearranged, for this purpose, as near as possible to the flow openings ofthe flow dividers 20 ₁, 20 ₂, in order so to provide an as short aspossible inlet, or outlet, as the case may be, region in the flowdividers and, thus, in total, to provide an as short as possibleinstalled length L₁₁ of the measuring transducer, especially aninstalled length L₁₁ of less than 3000 mm. For an as compact as possiblemeasuring transducer and especially also in the case of desired highmass flow rates of over 1000 t/h, according to another embodiment of theinvention, the installed length and the nominal diameter of themeasuring transducer are so dimensioned and matched to one another, thata nominal diameter to installed length ratio D₁₁/L₁₁ of the measuringtransducer, as defined by a ratio of the nominal diameter D₁₁ of themeasuring transducer to the installed length L₁₁ of the measuringtransducer is smaller than 0.3, especially smaller than 0.2 and/orgreater than 0.1. In the example of an embodiment shown here, at leastone middle segment 7 _(1A) of the transducer housing 7 ₁ is formed bymeans of a straight—here also circularly cylindrical and firstly threepart—tube, so that for manufacturing the transducer housing 7 ₁, forexample, also standardized, consequently cost effective, welded or cast,standard tubes, for example, of cast steel or forged steel, can be used.As additionally directly evident from the combination of FIGS. 1 and 2,the middle segment 7 _(1A) of the transducer housing 7 ₁ can be formed,in such case, for example, also by means of a tube having approximatelythe caliber of the pipeline to be connected to, consequentlycorresponding to a nominal diameter D₁₁ of the measuring transducer,especially a tube corresponding as regards caliber, wall thickness andmaterial of the pipeline to be connected to and, insofar, alsocorrespondingly matched as regards the allowed operating pressure.Particularly for the case, in which the tubular middle segment, as wellas also the flow dividers connected with the respective flanges in thein-, and outlet regions have, in each case, the same inner diameter, thetransducer housing can additionally also be formed in a manner such thatthe flanges are formed or welded on the ends of the tube forming themiddle segment, and that the flow dividers are formed by means of plateshaving the flow openings, especially plates somewhat spaced from theflanges and welded orbitally to the inner wall and/or by means of laserwelding.

For conveying the medium flowing, at least at times, through pipelineand measuring transducer, the measuring transducer of the inventioncomprises, additionally, a tube arrangement having exactly four curved,or bent, for example at least sectionally circular arc shaped, and/or,as shown here schematically, at least sectionally V-shaped, measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ held oscillatably in the transducer housing10. The four measuring tubes, in this case, measuring tubes of equallength and pairwise parallel, communicate, in each case, with thepipeline connected to the measuring transducer and are, at least attimes, especially also simultaneously, caused during operation tovibrate in at least one actively excited, oscillatory mode, theso-called wanted mode, suited for ascertaining the physical, measuredvariable. Of the four measuring tubes, a first measuring tube 18 ₁ openswith an inlet-side, first measuring tube end into a first flow opening20 _(1A) of the first flow divider 20 ₁ and with an outlet-side, secondmeasuring tube end into a first flow opening 20 _(2A) of the second flowdivider 20 ₂, a second measuring tube 18 ₂ opens with an inlet-side,first measuring tube end into a second flow opening 20 _(1B) of thefirst flow divider 20 ₁ and with an outlet-side, second measuring tubeend into a second flow opening 20 _(2B) of the second flow divider 20 ₂,a third measuring tube 18 ₃ opens with an inlet-side, first measuringtube end into a third flow opening 20 _(1C) of the first flow divider 20₁ and with an outlet-side, second measuring tube end into a third flowopening 20 _(2C) of the second flow divider 20 ₂ and a fourth measuringtube 18 ₄ opens with an inlet-side, first measuring tube end into afourth flow opening 20 _(1D) of the first flow divider 20 ₁ and with anoutlet-side, second measuring tube end into a fourth flow opening 20_(2D) of the second flow divider 20 ₂. The four measuring tubes 18 ₁, 18₂, 18 ₃, 18 ₄ are, thus, connected to the flow dividers 20 ₁, 20 ₂,especially equally constructed flow dividers 20 ₁, 20 ₂, to form flowpaths connected in parallel, and, indeed, in a manner enablingvibrations, especially bending oscillations, of the measuring tubesrelative to one another, as well as also relative to the transducerhousing. Additionally, it is provided, that the four measuring tubes 18₁, 18 ₂, 18 ₃, 18 ₄ are held oscillatably in the transducer housing 7₁—here, namely, on its middle segment 7 _(1A)—only by means of said flowdividers 20 ₁, 20 ₂. Suited as material for the tube walls of themeasuring tubes is, for example, stainless, in given cases, also highstrength, stainless steel, titanium, zirconium or tantalum, or alloysformed therewith or also super alloys, such as, for instance, Hastelloy,Inconel etc. Moreover, the material for the four measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄, however, can also be practically any other materialusually applied therefor or at least a material suitable therefor,especially such with an as small as possible thermal expansioncoefficient and an as high as possible yield point. Alternatively, or insupplementation, are according to an additional embodiment of theinvention, at least the first and second measuring tubes 18 ₁, 18 ₂ areof equal construction as regards the material of their tube walls,and/or as regards their geometric tube dimensions, especially ameasuring tube length, a tube wall thickness, a tube outer diameterand/or a caliber. Additionally, also at least the third and the fourthmeasuring tube 18 ₃, 18 ₄ are of equal construction as regards thematerial of their tube walls, and/or as regards their geometric tubedimensions, especially a measuring tube length, a tube wall thickness, atube outer diameter and/or a caliber, so that, as a result, the fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are, at least pairwise,essentially of equal construction. Preferably, the four measuring tubes18 ₁, 18 ₂, 18 ₃, 18 ₄ are of equal construction as regards the materialof their tube walls are, and/or as regards their geometric tubedimensions, especially a measuring tube length, a tube wall thickness, atube outer diameter, a form of their bending lines and/or a caliber,especially in such a manner, that, as a result, at least one minimumbending oscillation resonance frequency of each of the four measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ (empty or uniformly flowed-through by ahomogeneous medium) essentially equals the respective minimum bendingoscillation resonance frequencies of the remaining other measuringtubes.

In the case of the measuring transducer of the invention, the measuringtubes are, as directly evident also from the combination of FIGS. 2, 4 aand 4 b, additionally so embodied and arranged in the measuringtransducer, that the tube arrangement has, lying both between the firstmeasuring tube 18 ₁ and the third measuring tube 18 ₃ as well as alsobetween the second measuring tube 18 ₂ and the fourth measuring tube 18₄, a first imaginary longitudinal-section plane XZ, with respect towhich the tube arrangement is mirror symmetric, and that the tubearrangement has further, perpendicular to its imaginary firstlongitudinal-section plane XZ, and extending both between the firstmeasuring tube 18 ₁ and second measuring tube 18 ₂ as well as alsobetween the third measuring tube 18 ₃ and fourth measuring tube 18 ₄, asecond imaginary longitudinal-section plane YZ, with respect to whichthe tube arrangement likewise is mirror symmetric. As a result of this,not only are stresses generated by possible thermally related expansionof the measuring tubes within the tube arrangement minimized, but alsotransverse forces possibly induced by the bending oscillations of thebent measuring tubes within the tube arrangement and acting essentiallyperpendicularly to the line of intersection of the two aforementioned,imaginary, longitudinal-section planes can be largely neutralized, notlastly also those transverse forces mentioned, among other things, alsoin the initially mentioned EP-A 1 248 084 and U.S. Pat. No. 7,350,421,directed essentially perpendicularly to the first imaginarylongitudinal-section plane XZ. Especially also as evident from FIGS. 4a, 4 b, 5 a, 5 b, in the example of an embodiment shown here, each ofthe four measuring tubes has a measuring tube peak, defined as thegreatest perpendicular distance of the respective measuring tube fromthe first imaginary longitudinal section plane XZ. In the remainingincludes the tube arrangement has, as also directly evident from thecombination of FIGS. 4 a-6 b, an imaginary cross sectional plane XYperpendicular both to the first imaginary longitudinal section plane XZas well as also to the second imaginary longitudinal section plane YZ.In an advantageous embodiment of the invention, the tube arrangement isadditionally so embodied, that a center of mass of the tube arrangementlies in the imaginary cross sectional plane XY, or that the tubearrangement is mirror symmetric relative to the imaginary crosssectional plane XY, for instance, in such a manner, that the imaginarycross sectional plane XY intersects each of the four measuring tubes inits respective measuring tube peak.

For additional symmetrization of the measuring transducer and, thus,also for the additional simplifying of its construction, the two flowdividers 20 ₁, 20 ₂ are, according to an additional embodiment of theinvention, additionally so embodied and so arranged in the measuringtransducer, that, as also schematically presented in FIGS. 4 a and 4 b,an imaginary first connecting axis Z₁ of the measuring transducerimaginarily connecting the first flow opening 20 _(1A) of the first flowdivider 20 ₁ with the first flow opening 20 _(2A) of the second flowdivider 20 ₂ extends parallel to an imaginary second connecting axis Z₂of the measuring transducer imaginarily connecting the second flowopening 20 _(1B) of the first flow divider 20 ₁ with the second flowopening 20 _(2B) of the second flow divider 20 ₂, and that an imaginarythird connecting axis Z₃ of the measuring transducer imaginarilyconnecting the third flow opening 20 _(1C) of the first flow divider 20₁ with the third flow opening 20 _(2C) of the second flow divider 20 ₂extends parallel to an imaginary fourth connecting axis Z₄ of themeasuring transducer imaginarily connecting the fourth flow opening 20_(1B) the first flow divider 20 ₁ with the fourth flow opening 202E thesecond flow divider 20 ₂. As shown in FIGS. 4 a and 4 b, the flowdividers are additionally so embodied and so arranged in the measuringtransducer, that the connecting axes Z₁, Z₂, Z₃, Z₄ also are parallel toa principal flow axis L of the measuring transducer essentially aligningwith the pipeline and/or coincident with the aforementioned line ofintersection of the two imaginary longitudinal-section planes XZ, YZ ofthe tube arrangement. Furthermore, the two flow dividers 20 ₁, 20 ₂ canadditionally also be so embodied and so arranged in the measuringtransducer, that a first imaginary longitudinal-section plane XZ₁ of themeasuring transducer, within which the first imaginary connecting axisZ₁ and the second imaginary connecting axis Z₂ extend, is parallel to asecond imaginary longitudinal-section plane XZ₂ of the measuringtransducer, within which the imaginary third connecting axis Z₃ and theimaginary fourth connecting axis Z₄ extend.

Moreover, the measuring tubes are, according to an additional embodimentof the invention, additionally so embodied and so arranged in themeasuring transducer, that the imaginary first longitudinal-sectionplane XZ of the tube arrangement, as, among other things, also evidentfrom the combination of FIGS. 3 a and 4 a, lies between theaforementioned first imaginary longitudinal-section plane XZ₁ of themeasuring transducer and the aforementioned second imaginarylongitudinal-section plane XZ₂ of the measuring transducer, for example,also such that the first longitudinal-section plane XZ of the tubearrangement is parallel to the first and second longitudinal-sectionplanes XZ₁,XZ₂ of the measuring transducer. Additionally, the measuringtubes are so embodied and arranged in the measuring transducer, thatequally also the second imaginary longitudinal-section plane YZ of thetube arrangement extends between the third imaginarylongitudinal-section plane YZ₁ of the measuring transducer and thefourth imaginary longitudinal-section plane YZ₂ of the measuringtransducer, for instance, in such a manner, that the second imaginarylongitudinal-section plane YZ of the tube arrangement is parallel to thethird imaginary longitudinal-section plane YZ₁ of the measuringtransducer and parallel to the fourth imaginary longitudinal-sectionplane YZ₂ of the measuring transducer. In the example of an embodimentshown here, the tube arrangement is, as directly evident from thecombination of FIGS. 4 a, 4 b, 5 a, 5 b and 6 a, additionally soembodied and so placed in the transducer housing, that, as a result, notonly the shared line of intersection of the first and second imaginarylongitudinal section planes XZ, YZ of the tube arrangement is parallel,or coincident with, the longitudinal axis L, but, also, a shared line ofintersection of the first longitudinal section plane XZ and the crosssectional plane XY is parallel to an imaginary transverse axis Q of themeasuring transducer perpendicular to the longitudinal axis L and ashared line of intersection of the second longitudinal section plane YZand the cross sectional plane XY is parallel to an imaginary verticalaxis H of the measuring transducer perpendicular to the longitudinalaxis L.

In an additional advantageous embodiment of the invention, the flowopenings of the first flow divider 20 ₁ are additionally so arranged,that those imaginary areal center of gravity, which belong to the—herecircularly shaped—cross sectional areas of the flow openings of thefirst flow divider form the vertices of an imaginary rectangle or of animaginary square, wherein said cross sectional areas lie, again, in ashared imaginary, cross sectional plane of the first flow dividerextending perpendicular to a longitudinal axis L of the measuringtransducer—, for example, a longitudinal axis extending within the firstlongitudinal-section plane XZ of the tube arrangement, or parallel to oreven coincident with the mentioned principal flow axis of the measuringtransducer—, or perpendicular to the longitudinal-section planes of themeasuring transducer. Additionally, also the flow openings of the secondflow divider 20 ₂ are so arranged, that imaginary areal centers ofgravity associated with—here likewise circularly shaped—cross sectionalareas of the flow openings of the second flow divider 20 ₂ form thevertices of an imaginary rectangle, or square, wherein said crosssectional areas lie, again, in a shared imaginary, cross sectional planeof the second flow divider extending perpendicular to the mentioned mainflow, or also longitudinal, axis, L of the measuring transducer, orperpendicular to the longitudinal-section planes of the measuringtransducer. In an additional embodiment of the invention, the measuringtubes are so bent and so arranged in the measuring transducer, that acaliber to height ratio D₁₈/Q₁₈ of the tube arrangement, defined by aratio of the caliber, D₁₈, of the first measuring tube to a maximallateral expanse of the tube arrangement Q₁₈, measured from a peak of thefirst measuring tube to a peak of the third measuring tube, or measuredfrom a peak of the second measuring tube to a peak of the fourthmeasuring tube, amounts to more than 0.05, especially more than 0.07and/or less than 0.35, especially less than 0.2.

For the purpose of implementing an as compact as possible measuringtransducer, especially also for the mentioned case, in which such shouldhave a comparatively large nominal diameter of 250 mm or more, and/orthat the measuring tubes are laterally comparatively spread out, thetransducer housing 7 ₁ can, as additionally directly evident from thecombination of FIGS. 1 and 2, in advantageous manner, additionally beformed by providing that the transducer housing 7 ₁ is formed by meansof a tube and housing caps. The tube is here, for the purpose ofsimplified handling, for example, firstly three part, thus threeindividual segments joined together, and has corresponding lateralopenings for the caps. The tube has—as already indicated—, for instance,the caliber of the pipeline to be connected to, thus a calibercorresponding to a nominal diameter D₁₁ of the measuring transducer. Thehousing caps 7 _(1B), 7 _(1C), especially equally-constructed housingcaps, are affixed, for instance, welded, laterally to the tubeultimately forming the middle segment of the transducer housing, andextend laterally from the middle segment to encase the segments of themeasuring tubes. Of the two housing caps 7 _(1B), 7 _(1C)—as evidentfrom the combination of FIGS. 1-4 a—e.g. a first housing cap 7 _(1B)caps a segment of the first measuring tube extending outwards on a firstside from the middle segment—especially a middle segment serving also assupport frame for the tube arrangement, and consequently formed as asupport tube—and a segment of the second measuring tube extendingoutwards on the first side from the middle segment and a second housingcap 7 _(1C), for instance, a second housing cap constructed equally tothe first housing cap, caps a segment of the third measuring tubeextending outwards from the middle segment on a second side lyingopposite to the first side and a segment of the fourth measuring tubeextending outwards from the middle segment on the second side. As aresult of this, the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, or thetherewith formed tube arrangement of the measuring transducer 11 are, asdirectly evident from the combination of FIGS. 1, 2 and 4 a completelyencased by the transducer housing 7 ₁—formed here by means of the middlesegment serving, especially, also as support tube, as well as by the twohousing caps laterally affixed thereto. For the aforementioned case, inwhich the transducer housing is formed by means of the tubular middlesegment and the thereto laterally affixed housing caps, the fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ and the transducer housing 7 ₁are, in an additional embodiment of the invention—especially also forthe purpose of minimizing the installed mass of the total measuringtransducer—matched to one another and additionally so dimensioned, thata support tube to measuring tube, inner diameter ratio of the measuringtransducer, defined by a ratio of the largest inner diameter of themiddle segment of the transducer housing formed as support tube to acaliber D₁₈ of the first measuring tube, is greater than 3 and/orsmaller than 5, especially smaller than 4.

Moreover, used as material for the transducer housing 7 ₁ can be steels,such as, for instance, structural steel, or stainless steel, or alsoother suitable, or usually suitable for such purpose, high strengthmaterials. For most applications of industrial measurements technology,especially also in the petrochemical industry, additionally alsomeasuring tubes of stainless steel, for example, also duplex steel,super duplex steel or another (high strength) stainless steel, cansatisfy the requirements relative to mechanical strength, chemicalresistance as well as thermal requirements, so that in numerous cases ofapplication the transducer housing 7 ₁, the flow dividers 20 ₁, 20 ₂, aswell as also the tube walls of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18₄ can, in each case, be of steel of, in each case, sufficiently highquality, which, especially relative to the material- and manufacturingcosts, as well as also the thermally related dilation behavior of themeasuring transducer 11 during operation, can be advantageous. Moreover,the transducer housing 7 ₁ additionally in advantageous manner can alsobe so embodied and so dimensioned, that, in the case of possible damagesto one or a number of the measuring tubes, e.g. through crack formationor bursting, outflowing medium can be completely retained in theinterior of the transducer housing 7 ₁ up to a required maximal positivepressure, for as long as desired, wherein such critical state can, as,for example, also mentioned in the initially cited U.S. Pat. No.7,392,709, be registered and signaled as early as possible by means ofcorresponding pressure sensors and/or based on operating parametersproduced by the mentioned transmitter electronics 12 internally duringoperation. For simplifying transport of the measuring transducer, or ofthe total in-line measuring device formed therewith, additionally, as,for example, also provided in the initially mentioned U.S. Pat. No.7,350,421, transport eyes can be provided on the inlet side and outletsides affixed externally on the transducer housing.

As already initially mentioned, the reaction forces required for themeasuring are effected in the measuring transducer 11 in the medium tobe measured by causing the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ tooscillate, for example, simultaneously, in an actively excitedoscillatory mode, the so-called wanted mode. For exciting oscillationsthe measuring tubes, especially also those in the wanted mode, themeasuring transducer further comprises an exciter mechanism 5 formed bymeans of at least one electro-mechanical, for example, electro-dynamic,oscillation exciter acting on the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18₄. Exciter mechanism 5 serves to cause each of the measuring tubesoperationally at least at times to execute oscillations, especiallybending oscillations, in the wanted mode and to maintain suchoscillations with oscillation amplitude sufficiently large for producingin the medium, and for registering, the above named reaction forcessuitable for the particular measuring, or these wanted oscillations. Theat least one oscillation exciter, and thus the therewith formed excitermechanism, serves, in such case, especially for converting an electricalexcitation power P_(exc) fed from the transmitter electronics—, forinstance, by means of at least one electrical driver signal—into such,e.g. pulsating or harmonic, exciter forces F_(exc), which act assimultaneously as possible, uniformly, however, with opposite sense, onat least two of the measuring tubes, for instance, the first and secondmeasuring tubes and, in given cases, are also coupled mechanically fromthe two measuring tubes further onto the other two measuring tubes, andso effect oscillations in the wanted mode. The exciter forces F_(exc)generated by converting electrical excitation power P_(exc) fed into theexciter mechanism can in manner known, per se, to those skilled in theart, e.g. by means of an operating circuit provided in the transmitterelectronics 12 and lastly delivering the driver signal, be tuned, forinstance, by means of electrical current- and/or voltage controllersimplemented in the operating circuit as regards their amplitude and,e.g. by means of an in operating circuit likewise provided phase controlloop (PLL), as regards their frequency; compare, for this, for example,also U.S. Pat. No. 4,801,897 or U.S. Pat. No. 6,311,136. In anadditional embodiment of the invention, it is, consequently,additionally provided, that the transmitter electronics, for generatingthe exciter forces, feeds required electrical excitation power into theexciter mechanism by means of at least one electrical driver signal, forexample, an at least at times periodic driver signal, supplied to theoscillation exciter, and, thus, the exciter mechanism, for example, viaconnecting lines. The driver signal is variable with at least one signalfrequency corresponding to an eigenfrequency of a natural mode ofoscillation of the tube arrangement, for instance, the mentioned V-modeor the mentioned X-mode. For example, the at least one driver signal canalso have a plurality of signal components with signal frequenciesdiffering from one another, of which at least one signal component (forinstance, one dominating as regards signal power) has a signal frequencycorresponding to an eigenfrequency of a natural mode of oscillation ofthe tube arrangement, in which each of the four measuring tubes executesbending oscillations, for example, thus the mentioned bendingoscillation mode of first type. Moreover, it can additionally beadvantageous—, for instance, for the purpose of fitting the fed-inexcitation power to that instantaneously actually necessary for asufficient oscillation amplitude—, to make the at least one driversignal variable relative to a maximal voltage level (voltage amplitude)and/or a maximal electrical current level (electrical currentamplitude)—, for instance, in such a manner, that, for example, excitercurrent flows through the cylindrical coil of the at least oneoscillation exciter driven by a variable exciter voltage provided bymeans of said driver signal.

Goal of the active exciting of the measuring tubes to oscillations is,in particular, especially also for the case, in which the measuringsystem ultimately formed by means of the measuring transducer should beused for measuring mass flow, to induce by means of the measuring tubesvibrating in the wanted mode sufficiently strong Coriolis forces in theflowing medium, such that, as a result, additionaldeformations—consequently deformations corresponding to an oscillatorymode of higher order of the tube arrangement—the so-called Coriolismode—of each of the measuring tubes can be effected with oscillationamplitude sufficient for the measuring. For example, the measuring tubes18 ₁, 18 ₂, 18 ₃, 18 ₄ can by means of the thereto held,electro-mechanical exciter mechanism be excited to, especiallysimultaneous, bending oscillations, especially at an instantaneousmechanical eigenfrequency of the tube arrangement formed by means of thefour measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, in the case of which theyare—at least predominantly—laterally deflected and, as directly evidentfor those skilled in the art from the combination of FIGS. 3 a, 3 b, 6a, 6 b, 7 a, 7 b, caused to oscillate pairwise essentiallyopposite-equally relative to one another. This, especially, in such amanner, that each of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ executesduring operation at the same time vibrations at least at times and/or atleast partially, in each case, formed as bending oscillations about animaginary oscillatory axis connecting the first and the, in each case,associated second measuring tube end of the respective measuring tube,in each case parallel to the mentioned connecting axes Z₁, Z₂, Z₃, Z₄,wherein the four oscillatory axes in the example of an embodiment shownhere are parallel to one another, as well as also to the imaginarylongitudinal axis L of the total measuring transducer imaginarilyconnecting the two flow dividers and passing through a center of mass ofthe measuring transducer. In other words, the measuring tubes can, asquite usual in the case of measuring transducers of vibration-typehaving one or more, bent measuring tubes be caused, in each case, tooscillate at least sectionally in the manner of a terminally clampedcantilever, consequently thus with cantilever, bending oscillations,around, in each case, an imaginary oscillation axis parallel to at leasttwo of the imaginary connecting axes Z₁, Z₂, Z₃, Z₄. In an embodiment ofthe invention, the exciter mechanism is additionally embodied in such amanner that, therewith, the first measuring tube 18 ₁ and the secondmeasuring tube 18 ₂ are excitable to execute relative to the secondimaginary longitudinal section plane YZ opposite equal, especially alsorelative to the second imaginary longitudinal section plane YZsymmetric, bending oscillations and the third measuring tube 18 ₃ andthe fourth measuring tube 18 ₄ are excitable to execute relative to thesecond imaginary longitudinal section plane YZ opposite equal,especially also relative to the second imaginary longitudinal sectionplane YZ symmetric, bending oscillations. Alternatively thereto or insupplementation thereof, the exciter mechanism is according to anadditional embodiment of the invention additionally embodied in such amanner that, therewith, the first measuring tube 18 ₁ and the thirdmeasuring tube 18 ₃ are excitable to execute relative to the secondimaginary longitudinal section plane YZ opposite equal, for example,also relative to the second imaginary longitudinal section plane YZsymmetric, bending oscillations and the second measuring tube 18 ₂ andthe fourth measuring tube 18 ₄ are excitable to execute relative to thesecond imaginary longitudinal section plane YZ opposite equal, forexample, relative to the second imaginary longitudinal section plane YZsymmetric, bending oscillations.

In an additional embodiment of the invention, the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄ are excited during operation by means of the excitermechanism 5 additionally at least partially, especially predominantly,to wanted mode bending oscillations, which have a bending oscillationfrequency, which, for instance, equals an instantaneous mechanicalresonance frequency of the tube arrangement comprising the fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, consequently corresponds to aninstantaneous eigenfrequency of a bending oscillation mode of the tubearrangement, or which lies at least in the vicinity of such an eigen- orresonance frequency. The instantaneous mechanical resonance frequenciesof bending oscillations are, in such case, as is known, dependent inspecial measure on size, shape and material of the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄, as well as also on an instantaneous density of themedium flowing through the measuring tubes and can, thus, duringoperation of the measuring transducer, vary within a quite some numberof kilohertz wide, wanted frequency band. In the case of exciting themeasuring tubes at an instantaneous resonance frequency, thus, on theone hand, based on the instantaneously excited oscillation frequency, anaverage density of the medium flowing through the four measuring tubescan be instantaneously easily ascertained. On the other hand, so also,the electrical power instantaneously required for maintaining theoscillations excited in the wanted mode can be minimized. Especially,the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, are caused tooscillate, driven by the exciter mechanism, additionally, at least attimes, with essentially equal oscillation frequency, especially, in eachcase, one and the same natural mechanical eigenfrequency, and, thus, ashared, natural mechanical eigenfrequency. In advantageous manner, theoscillatory behavior of the tube arrangement formed by means of the fourmeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, as well as also the driversignals controlling the exciter mechanism, are additionally so matchedto one another, that at least the oscillations of the four measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ excited in the wanted mode so are developedthat the first and second measuring tubes 18 ₁, 18 ₂ oscillate—, forinstance, in the manner of two tuning fork tines essentially oppositeequally to one another, consequently at least in the imaginary crosssectional plane XY with an opposing phase shift of, for instance, 180°,and also the third and the fourth measuring tube 18 ₃, 18 ₄ equallyoscillate essentially opposite equally to one another.

Investigations on measuring systems with a measuring transducer of thetype being discussed have additionally surprisingly shown that as wantedmode, especially also for ascertaining the mass flow rate as well as thedensity of the medium conveyed in the measuring transducer, especially,that tube arrangement inherent, natural, oscillatory mode is suited—inthe following referred to as the bending oscillation, fundamental modeof first type or also as the V-mode oscillation—, in which, as alsoshown schematically in FIG. 7 a, the first measuring tube and the secondmeasuring tube execute relative to the second imaginary longitudinalsection plane YZ opposite equal bending oscillations about, in eachcase, a static rest position associated with the respective measuringtube, and in which the third measuring tube and the fourth measuringtube execute relative to the second imaginary longitudinal section planelikewise opposite equal bending oscillations about, in each case, astatic rest position associated with the respective measuring tube, and,indeed, such that—relative to the second imaginary longitudinal sectionplane YZ—said bending oscillations of the first measuring tube are alsoopposite equal to said bending oscillations of the third measuring tube,and that—relative to the second imaginary longitudinal section planeYZ—said bending oscillations of the second measuring tube are alsoopposite equal to said bending oscillations of the fourth measuringtube. The (here likewise formed as cantilever, bending oscillationsaround, in each case, an imaginary oscillation axis parallel to at leasttwo of the imaginary connecting axes and causing the tube arrangement inprojection on the cross sectional plane XY to appear, at times, V-shapedletting (compare FIG. 7 a)) opposite equal bending oscillations of thefirst and second measuring tubes, or of the third and fourth measuringtube, in the V-mode are, in the case of a symmetrically constructed tubearrangement and a uniformly flowed through tube arrangement,additionally symmetrically developed relative to the second imaginarylongitudinal section plane YZ. The special suitability of the V-mode aswanted mode for measuring transducers with four bent measuring tubescould, in such case, especially also be attributed especially to the forthe oscillatory behavior of the measuring transducer—considered bothspatially as well as also in time—, in such case, as a whole, veryfavorable resulting stress distribution in the measuring transducer,especially also in the region of the two flow dividers, as well as alsoto the equally favorable, consequently very small, oscillation relateddeformations of the measuring transducer in general, as well as also theflow dividers in particular.

Besides the aforementioned V-mode, the tube arrangement has additionallyalso a natural bending oscillation mode of second type—referenced in thefollowing as the X-mode—, in which—as shown schematically in FIG. 7b—the first measuring tube and the second measuring tube executerelative to the second imaginary longitudinal section plane YZ oppositeequal bending oscillations about the, in each case, associated staticrest position and in which the third measuring tube and the fourthmeasuring tube execute relative to the second imaginary longitudinalsection plane YZ opposite equal bending oscillations about, in eachcase, the associated static rest position, in contrast with the bendingoscillations in the V-mode, however, in the manner, that—relative to thesecond imaginary longitudinal section plane YZ—said bending oscillationsof the first measuring tube are also opposite equal to said bendingoscillations of the fourth measuring tube, and that—relative to thesecond imaginary longitudinal section plane YZ—said bending oscillationsof the second measuring tube are also opposite equal to said bendingoscillations of the third measuring tube. In the case of symmetricallyconstructed and uniformly flowed through tube arrangements, moreover,also the (here, in turn, as cantilever, bending oscillations formedaround, in each case, an imaginary oscillation axis parallel to at leasttwo of the imaginary connecting axes and causing the tube arrangement inprojection on the cross sectional plane XY to appear, at times, X-shaped(compare FIG. 7 b)) bending oscillations in the X-mode are likewisesymmetric relative to the second imaginary longitudinal section planeYZ. In order to assure a separate, especially also defined, exciting ofthe V-mode, or of the X-mode, over an as broad as possible operatingrange of the measuring transducer (characterized by, among other thingsduring operation, fluctuating densities, mass flow rates, temperaturedistributions in the measuring transducer, etc.), according to anadditional embodiment of the invention, the tube arrangement formed bymeans of the four measuring tubes, consequently the therewith formed,measuring transducer, is so dimensioned, that an eigenfrequency f_(18V);of the bending oscillation mode of first type (V-mode) measurable, forexample, in the case of a tube arrangement filled completely with water,is different from an eigenfrequency f_(18X) of the bending oscillationmode of second type (X-mode) measurable especially in the case of a tubearrangement filled completely with water, and, respectively at the sametime as the eigenfrequency f_(18V) of the bending oscillation mode offirst type (V-mode), for example, such that the eigenfrequenciesf_(18V); f_(18X); of the two said bending oscillation modes (V-mode,X-mode) deviate from one another by 10 Hz or more. Especially also forthe case of large nominal diameters of more than 150 mm, the tubearrangement is so embodied, that, said eigenfrequency f_(18V) of thebending oscillation mode of first type is more than 10 Hz greater thansaid eigenfrequency f_(18X) of the bending oscillation mode of secondtype. The exciter mechanism is, according to an additional embodiment ofthe invention, consequently, embodied in such a manner that, therewith,the first measuring tube 18 ₁ and the second measuring tube 18 ₂ areexcitable during operation to opposite equal bending oscillations andthe third measuring tube 18 ₃ and the fourth measuring tube 18 ₄ duringoperation to opposite equal bending oscillations, especially alsobending oscillations corresponding to the bending oscillation mode offirst type (V-mode) at its instantaneous eigenfrequency f_(18V), and,respectively, bending oscillations corresponding to the bendingoscillation mode of second type (X-mode) at its instantaneouseigenfrequency f_(18V), the latter bending oscillations, in given cases,also simultaneously with the bending oscillations corresponding to thebending oscillation mode of first type (V-mode).

In an additional embodiment of the invention the exciter mechanism 5 isformed by means of a first oscillation exciter 5 ₁ acting, especiallydifferentially, on the first measuring tube 18 ₁ and the secondmeasuring tube 18 ₂, especially also for the purpose of excitingopposite equal bending oscillations of the first and second measuringtube and/or of the third and fourth measuring tube. Additionally, it isprovided that serving as first oscillation exciter 5 ₁ is an oscillationexciter of electrodynamic type acting, especially differentially, on atleast two of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄. Accordingly,the first oscillation exciter 5 ₁ is formed additionally by means of apermanent magnet held on the first measuring tube and a cylindrical coilheld on the second measuring tube and permeated by the magnetic field ofthe permanent magnet, especially in the manner of a coil, plungingarrangement, in the case of which the cylindrical coil is arrangedcoaxially with the permanent magnet and the permanent magnet is embodiedas an armature plunging within the coil.

For the purpose of increasing the efficiency of the exciter mechanismand, respectively, for the purpose of increasing the exciter forcesgenerated therewith while simultaneously achieving an as symmetric aspossible construction, the exciter mechanism comprises, in a furtherdevelopment of the invention, additionally a second oscillation exciter5 ₂ acting, especially electrodynamically and/or differentially, on thethird measuring tube 18 ₃ and the fourth measuring tube 18 ₄. The secondoscillation exciter 5 ₂ is, in advantageous manner, embodied with equalconstruction to that of the first oscillation exciter 5 ₁, at leastinsofar as it works analogously to its principle of action, for example,thus likewise is of electrodynamic type. In an additional embodiment,the second oscillation exciter 5 ₂ is, consequently, formed by means ofa permanent magnet held on the third measuring tube and a cylindricalcoil held on the fourth measuring tube and permeated by the magneticfield of the permanent magnet. The two oscillation exciter 5 ₁, 5 ₂ ofthe exciter mechanism 5 can, in advantageous manner, be electricallyserial interconnected, especially in such a manner, that a common driversignal consequently excites simultaneous oscillations of the measuringtubes 18 ₁, 18 ₃, 18 ₂, 18 ₄, for instance, bending oscillations in theV-mode and/or in the X-mode. Particularly for the earlier mentionedcase, in which both bending oscillations in the V-mode as well as alsobending oscillations in the X-mode should be actively excited by meansof the two oscillation exciters 5 ₁, 5 ₂, it can be of advantage to sodimension the oscillation exciters 5 ₁, 5 ₂ and to so apply them to thetube arrangement, that, as a result, a transmission factor of the firstoscillation exciter 5 ₁, defined by a ratio of therein fed electricalexcitation power to an exciter force effecting oscillations of themeasuring tubes produced therewith, is different, at least within afrequency band including the V-mode and the X-mode, from a transmissionfactor of the second oscillation exciter 5 ₂, defined by a ratio oftherein fed electrical excitation power to an exciter force effectingoscillations of the measuring tubes produced therewith, for instance, insuch a manner, that said transmission factors deviate from one anotherby 10% or more. This enables, for example, also a separated exciting ofV- and X-modes, especially also in the case of serial switching of thetwo oscillation exciter 5 ₁, 5 ₂ and/or supplying the two oscillationexciter 5 ₁, 5 ₂ with a single, shared, driver signal, and can beachieved in the case of electrodynamic oscillation exciters 5 ₁, 5 ₂ invery simple manner e.g. by application of cylindrical coils withdifferent impedances, or different turns numbers and/or by differentlydimensioned permanent magnets, or permanent magnets of differentmagnetic materials. It should here additionally be mentioned that,although the oscillation exciter, or the oscillation exciters, of theexciter mechanism shown here in the example of an embodiment act, ineach case, for instance, centrally on the respective measuring tubes,alternatively or in supplementation, also oscillation exciter actinginstead on the inlet and on the outlet sides of the particular measuringtube can be used, for instance, in the manner of the exciter mechanismsproposed in U.S. Pat. No. 4,823,614, U.S. Pat. No. 4,831,885, or theUS-A 2003/0070495.

As evident from FIGS. 2, 4 a, 4 b, 5 a and 5 b and usual in the case ofmeasuring transducers of the type being discussed, additionally providedin the measuring transducer 11 is a sensor arrangement 19, for example,an electrodynamic sensor arrangement, reacting to vibrations of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, or 18 ₄, especially inlet, andoutlet-side vibrations, especially bending oscillations excited by meansof the exciter mechanism 5, for producing oscillation signalsrepresenting vibrations, especially bending oscillations, of themeasuring tubes and influenced, for example, as regards a frequency, asignal amplitude and/or a phase position—relative to one another and/orrelative to the driver signal—by the measured variable to be registered,such as, for instance, the mass flow rate and/or the density and aviscosity of the medium, respectively.

In an additional embodiment of the invention, the sensor arrangement isformed by means of an inlet-side, first oscillation sensor 19 ₁,especially an electrodynamic, first oscillation sensor and/or a firstoscillation sensor differentially registering at least oscillations ofthe first measuring tube 18 ₁ relative to the second measuring tube 18₂, as well as an outlet-side, second oscillation sensor 19 ₂, especiallyan electrodynamic, second oscillation sensor and/or a second oscillationsensor differentially registering at least oscillations of the firstmeasuring tube 18 ₁ relative to the second measuring tube 18 ₂, whichtwo oscillation sensors deliver, respectively, a first, and a second,oscillation signal reacting to movements of the measuring tubes 18 ₁, 18₂, 18 ₃, 18 ₄, especially their lateral deflections and/or deformations.This, especially, in such a manner, that at least two of the oscillationsignals delivered by the sensor arrangement 19 have a phase shiftrelative to one another, which corresponds to, or depends on, theinstantaneous mass flow rate of the medium flowing through the measuringtubes, as well as, in each case, a signal frequency, which depends on aninstantaneous density of the medium flowing in the measuring tubes. Thetwo oscillation sensors 19 ₁, 19 ₂, for example, oscillation sensorsconstructed equally to one another, can, for such purpose—such as quiteusual in the case of measuring transducers of the type beingdiscussed—be placed essentially equidistantly from the first oscillationexciter 5 ₁ in the measuring transducer 11. Moreover, the oscillationsensors of the sensor arrangement 19 can, at least, insofar as they areof equal construction to that of the at least one oscillation exciter ofthe exciter mechanism 5, work analogously to its principle of action,for example, thus be likewise of electrodynamic type. In a furtherdevelopment of the invention, the sensor arrangement 19 is additionallyformed also by means of an inlet-side, third oscillation sensor 19 ₃,especially an electrodynamic, oscillation sensor and/or an oscillationsensor differentially registering oscillations of the third measuringtube 18 ₃ relative to the fourth measuring tube 18 ₄, as well as anoutlet-side, fourth oscillation sensor 19 ₄, especially anelectrodynamic, fourth oscillation sensor 19 ₄ and/or an electrodynamicoscillation sensor differentially registering oscillations of the thirdmeasuring tube 18 ₃ relative to the fourth measuring tube 18 ₄. Foradditional improving of the signal quality, as well as also forsimplifying the transmitter electronics 12 receiving the measurementsignals, furthermore, the first and third oscillation sensors 19 ₁, 19 ₃can be electrically in series interconnected, for example, in such amanner, that a combined oscillation signal represents combinedinlet-side oscillations of the first and third measuring tubes 18 ₁, 18₃ relative to the second and fourth measuring tubes 18 ₂, 18 ₄.Alternatively or in supplementation, also the second and fourthoscillation sensors 19 ₂, 19 ₄ can be electrically in seriesinterconnected in such a manner, that a combined oscillation signal ofboth oscillation sensors 19 ₂, 19 ₄ represents combined outlet-sideoscillations of the first and third measuring tubes 18 ₁, 18 ₃ relativeto the second and fourth measuring tubes 18 ₂, 18 ₄.

For the aforementioned case, that the oscillation sensors of the sensorarrangement 19, especially oscillation sensors constructed equally toone another, should register oscillations of the measuring tubesdifferentially and electrodynamically, the first oscillation sensor 19 ₁is formed by means of a permanent magnet held to the first measuringtube—here in the region of oscillations to be registered on the inletside—and a cylindrical coil permeated by the magnetic field of thepermanent magnet and held to the second measuring tube—herecorrespondingly likewise in the region of oscillations to be registeredon the inlet side—, and the second oscillation sensor 19 ₂ is formed bymeans of a permanent magnet held—in the region of oscillations to beregistered on the outlet side—to the first measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held to the second measuring tube—here correspondingly likewise inthe region of oscillations to be registered on the outlet side. Equally,additionally also the, in given cases, provided, third oscillationsensor 19 ₃ can correspondingly be formed by means of a permanent magnetheld to the third measuring tube and a cylindrical coil permeated by themagnetic field of the permanent magnet and held to the fourth measuringtube, and the, in given cases, provided, fourth oscillation sensor 19 ₄by means of a permanent magnet held to the third measuring tube and acylindrical coil permeated by the magnetic field of the permanent magnetand held to the fourth measuring tube.

It is to be noted here additionally that, although, in the case of theoscillation sensors of the sensor arrangement 19 illustrated in theexample of an embodiment, the oscillation sensor is, in each case, ofelectrodynamic type, thus, in each case, formed by means of acylindrical magnet coil affixed to one of the measuring tubes and atherein plunging permanent magnet correspondingly affixed to anoppositely lying measuring tube, additionally also other oscillationsensors known to those skilled in the art, such as e.g. optoelectronicsensors, can be used for forming the sensor arrangement. Furthermore,such as quite usual in the case of measuring transducers of the typebeing discussed, supplementally to the oscillation sensors, other,especially auxiliary sensors, or sensors registering disturbancevariables, can be provided in the measuring transducer, such as e.g.acceleration sensors for registering movements of the total measuringsystem caused by external forces and/or asymmetries in the tubearrangement, strain gages for registering expansions of one or more ofthe measuring tubes and/or the transducer housing, pressure sensors forregistering a static pressure reigning in the transducer housing and/ortemperature sensors for registering temperatures of one or more of themeasuring tubes and/or the transducer housing, by means of which, forexample, the ability of the measuring transducer to function and/orchanges of the sensitivity of the measuring transducer to the measuredvariables primarily to be registered, especially the mass flow rateand/or the density, as a result of cross sensitivities, or externaldisturbances, can be monitored and, in given cases, correspondinglycompensated. For assuring an as high as possible sensitivity of themeasuring transducer to the mass flow, according to an additionalembodiment of the invention, the measuring tubes and the oscillationsensors are so arranged in the measuring transducer, that a measuringlength, L₁₉, of the measuring transducer corresponding to a separationbetween the first oscillation sensor 19 ₁ and the second oscillationsensor 19 ₂ measured along a deflection curve of the first measuringtube amounts to more than 500 mm, especially more than 600 mm.Particularly for creating an as compact as possible, nevertheless,however, for mass flow, an as sensitive as possible, measuringtransducer, according to an additional embodiment of the invention, theoscillation sensors 19 ₁, 19 ₂, matched to the installed length L₁₁ ofthe measuring transducer, are so arranged in the measuring transducer,that a measuring length to installed length ratio L₁₉/L₁₁ of themeasuring transducer, which is defined by a ratio of the measuringlength to the installed length of the measuring transducer, amounts tomore than 0.3, especially more than 0.4 and/or less than 0.7.Alternatively, or in supplementation, the oscillation sensors are,according to an additional embodiment of the invention, matched to themeasuring tubes, so placed in the measuring transducer, that a caliberto measuring length ratio D₁₈/L₁₉, of the measuring transducer, which isdefined by a ratio of the caliber D₁₈ of the first measuring tube to thementioned measuring length L₁₉ of the measuring transducer, amounts tomore than 0.05, especially more than 0.09.

The sensor arrangement 19 is additionally, as usual in the case of suchmeasuring transducers, coupled in suitable manner, for example,hardwired via connecting lines, with a measuring circuit correspondinglyprovided in the transmitter electronics, for example, a measuringcircuit formed by means of at least one microprocessor and/or by meansof at least one digital signal processor. The measuring circuit receivesthe oscillation signals of the sensor arrangement 19 and generatestherefrom, in given cases, also taking into consideration electricalexcitation power fed by means of the at least one driver signal into theexciter mechanism, and, consequently, also therein converted, theinitially mentioned measured values, which can represent, for example, amass flow rate, a totalled mass flow and/or a density and/or a viscosityof the medium to be measured, and which, in given cases, can bedisplayed on-site and/or also sent in the form of digital measured datato a data processing system superordinated to the measuring system andthere correspondingly further processed. Especially, the measuringcircuit, and, consequently, the therewith formed transmitterelectronics, are additionally provided and designed, based on electricalexcitation power converted in the exciter mechanism, to generate, forexample, periodically recurringly and/or on query, a viscosity measuredvalue representing the viscosity of the flowing medium and/or, based onoscillation signals delivered by the measuring transducer, to generate,for example, periodically recurringly and/or on query, a mass flowmeasured value representing the mass flow rate of the flowing mediumand/or, for example, periodically recurringly and/or on calling, adensity measured value representing the density of the flowing medium.

The above mentioned application of differentially acting, oscillationexciters, or oscillation sensors introduces, among other things, alsothe advantage, that for operating the measuring transducer of theinvention, also such established measuring, and operating, circuits canbe used, such as have found broad application, for example, already inconventional Coriolis, mass flow and/or density measuring devices.

The transmitter electronics 12, including the therein realizedmeasuring, and operating, circuits, can, furthermore, be accommodated,for example, in a separate electronics housing 7 ₂, which is arrangedremoved from the measuring transducer or, such as shown in FIG. 1, isaffixed directly on the measuring transducer 1, for example, externallyon the transducer housing 7 ₁, in order to form a single compact device.In the case of the here illustrated example of an embodiment,consequently, placed on the transducer housing 7 ₁ is, additionally, aneck-like, transition piece serving for holding the electronics housing7 ₂. Within the transition piece can additionally be arranged afeedthrough for the electrical connecting lines between measuringtransducer 11, especially the therein placed oscillation exciters andsensors, and the mentioned transmitter electronics 12. The feedthroughis manufactured to be hermetically sealed and/or pressure resistant, forexample, by means of glass, and/or plastic potting compound.

As already multiply mentioned, the in-line measuring device and, thus,also the measuring transducer 11, is provided, especially, formeasurements also of high mass flows of more than 1000 t/h in a pipelineof large caliber of more than 250 mm. Taking this into consideration,according to an additional embodiment of the invention, the nominaldiameter of the measuring transducer 11, which, as already mentioned,corresponds to a caliber of the pipeline, in whose course the measuringtransducer 11 is to be used, is so selected, that it amounts to morethan 50 mm, especially, however, is greater than 100 mm. Additionally,according to a further embodiment of the measuring transducer, it isprovided, that each of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ has,in each case, a caliber D₁₈ corresponding to a particular tube innerdiameter, which amounts to more than 40 mm. Especially, the measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are additionally so embodied, that each hasa caliber D₁₈ of more than 60 mm. Alternatively thereto or insupplementation thereof, the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are,according to another embodiment of the invention, additionally sodimensioned, that they have, in each case, a measuring tube length L₁₈of at least 1000 mm. The measuring tube length L₁₈ corresponds, in thehere illustrated example of an embodiment with equal length measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, in each case, to a length of a section ofthe deflection curve of the first measuring tube extending between thefirst flow opening of the first flow divider and the first flow openingof the second flow divider. Especially, the measuring tubes 18 ₁, 18 ₂,18 ₃, 18 ₄ are, in such case, so designed, that their measuring tubelength L₁₈ is, in each case, greater than 1200 mm. Accordingly, thereresults, at least for the mentioned case, that the measuring tubes 18 ₁,18 ₂, 18 ₃, 18 ₄ are composed of steel, in the case of the usually usedwall thicknesses of over 1 mm, a mass of, in each case, at least 20 kg,especially more than 30 kg. One tries, however, to keep the empty massof each of the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ smaller than 50kg.

In consideration of the fact that, as already mentioned, each of themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, in the case of the measuringtransducer of the invention, weighs well over 20 kg and, in such case,such as directly evident from the above dimensional specifications, canhave a capacity of easily 10 or more, the tube arrangement comprisingthen the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ can, at least inthe case of medium with high density flowing through, reach a total massof far over 80 kg. Especially in the case of the application ofmeasuring tubes with comparatively large caliber D₁₈, large wallthickness and large measuring tube length L₁₈, the mass of the tubearrangement formed by the measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ candirectly, however, also be greater than 100 kg or, at least with mediumflowing through, e.g. oil or water, be more than 120 kg. As a result ofthis, an empty mass M₁₁ of the measuring transducer amounts, in total,also to far more than 200 kg, and, in the case of nominal diameters D₁₁of significantly greater than 250 mm, even more than 300 kg. As aresult, the measuring transducer of the invention can have a mass ratioM₁₁/M₁₈ of an empty mass M₁₁ of the total measuring transducer to anempty mass M₁₈ of the first measuring tube of easily greater than 10,especially greater than 15.

In order, in the case of the mentioned high empty mass M₁₁ of themeasuring transducer, to employ the therefor, in total, applied materialas optimally as possible and, thus, to utilize the—most often also veryexpensive—material, in total, as efficiently as possible, according toan additional embodiment, the nominal diameter D₁₁ of the measuringtransducer is so dimensioned relative to its empty mass M₁₁, that a massto nominal diameter ratio M₁₁/D₁₁ of the measuring transducer 11, asdefined by a ratio of the empty mass M₁₁ of the measuring transducer 11to the nominal diameter D₁₁ of the measuring transducer 11, is smallerthan 2 kg/mm, especially as much as possible, however, smaller than 1kg/mm. In order to assure a sufficiently high stability of the measuringtransducer 11, the mass to nominal diameter ratio M₁₁/D₁₁ of themeasuring transducer 11 is, at least in the case use of the abovementioned conventional materials, however, to be chosen as much aspossible greater than 0.5 kg/mm. Additionally, according to anadditional embodiment of the invention, for additional improvement ofthe efficiency of the installed material, the mentioned mass ratioM₁₁/M₁₈ is kept smaller than 25.

For creation of a nevertheless as compact as possible measuringtransducer of sufficiently high oscillation quality factor and as littlepressure drop as possible, according to an additional embodiment of theinvention, the measuring tubes are so dimensioned relative to the abovementioned, installed length L₁₁ of the measuring transducer 11, that acaliber to installed length ratio D₁₈/L₁₁ of the measuring transducer,as defined by a ratio of the caliber D₁₈ at least of the first measuringtube to the installed length L₁₁ of the measuring transducer 11, amountsto more than 0.02, especially more than 0.05 and/or less than 0.09,especially less than 0.07. Alternatively or in supplementation, themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are so dimensioned relative tothe above mentioned installed length L₁₁ of the measuring transducer,that a measuring tube length to installed length ratio L₁₈/L₁₁ of themeasuring transducer, as defined by a ratio of the above-referencedmeasuring tube length L₁₈ at least of the first measuring tube to theinstalled length L₁₁ of the measuring transducer, amounts to more than0.7, especially more than 0.8 and/or less than 1.2.

For the purpose of tuning oscillation characteristics of the tubearrangement, especially also for the purpose of an as simple as possibleand, equally as well, an effective implementing of a sufficientseparating of the mentioned V-mode from the X-mode relative to theireigenfrequencies f_(18V); f_(18X), on the one hand, as well as, on theother hand, also for the purpose of improving the mechanical coupling ofthe four measuring tubes for equalizing the simultaneously executedoscillations of the four measuring tubes, at least the actively excitedbending oscillations of the wanted mode, for instance, also in the caseof possible inequalities due to component tolerances, the measuringtransducer further comprises, in an additional embodiment of theinvention, a first coupling element 24 ₁ of first type spaced both fromthe first flow divider as well as also from the second flow divider andaffixed on the inlet side to each of the four measuring tubes, forexample, a first coupling element 24 ₁ having an essentially X-shapedbasic shape or, as in FIG. 4 a or 4 b schematically presented, anessentially H-shaped basic shape, for tuning eigenfrequencies of naturaloscillation modes of the tube arrangement, as well as a second couplingelement 24 ₂ of first type spaced both from the first flow divider aswell as also from the second flow divider and affixed on the outlet sideto each of the four measuring tubes, for instance, a second couplingelement 24 ₂ essentially constructed equally to the first couplingelement 24 ₁ of first type, in given cases, also having an essentiallyX-shaped or essentially H-shaped basic shape, for tuningeigenfrequencies of natural oscillation modes of the tube arrangement.Each of the two coupling elements of first type can, in such case,additionally be so embodied and, in each case, so affixed to themeasuring tubes, that its projection onto the mentioned imaginary crosssectional plane XY of the measuring transducer is X-shaped, or that, aspresented in FIGS. 4 a and 4 b, its projection onto said cross sectionalplane XY is H-shaped. The coupling elements 24 ₁ of first type can, forexample, in each case, be formed by means of plate shaped elements or,as schematically presented in FIGS. 4 a, 4 b, produced by means of amonolithic blanked, bent part. The two coupling elements of first typeare in the example of an embodiment shown in FIG. 4 a, 4 b, or 5 a, 5 badditionally so embodied and placed on the measuring tubes, that theyare essentially symmetrically relative to the mentioned first imaginarylongitudinal section plane XZ of the measuring transducer, or relativeto the mentioned second imaginary longitudinal section plane YZ of themeasuring transducer, consequently, thus, the first imaginarylongitudinal section plane XZ and/or the second imaginary longitudinalsection plane YZ are/is, in each case, also a plane of symmetry of eachof the two coupling elements of first type. The two coupling elements offirst type in the measuring transducer are, moreover, also preferablysymmetrical relative to the mentioned imaginary cross sectional plane XYof the measuring transducer and, consequently equidistant and parallelextending relative to said cross sectional plane XY. In caserequired,—for example, because the measuring transducer is provided formeasuring extremely hot media, or for measuring in applications withoperating temperature fluctuating over a broad range, for instance, as aresult of recurringly in-situ performed, cleaning procedures of themeasuring transducer (“cleaning in process”, “sterilizing in process”,etc.), and, as a result, mentionable thermal expansions of the measuringtubes are to be expected—the coupling elements 24 ₁, 24 ₂ of first typecan additionally be so embodied, that they expand essentially equally asthe thereby, in each case, coupled measuring tubes and/or that they aresufficiently flexible at least relative to forces, which extend in thedirection of a line of action through the peaks of the two measuringtubes connected with one another by the particular coupling elements ofsecond type, for instance, coincident with, or parallel to, thementioned imaginary vertical axis V. The flexibility can be implemented,for example, by slits correspondingly formed in the particular couplingelement—, for instance, extending essentially transversely toaforementioned line of action. Alternatively, or in supplementation toslits formed in the coupling elements, according to another embodimentof the invention, each of the two coupling elements of first type is, asdirectly evident from the combination of FIGS. 4 a, 4 b, 5 a, 5 b,bowed, especially for the purpose of achieving a sufficient flexibilityin the direction of the imaginary vertical axis H. This is accomplished,especially, in such a manner that each of the two coupling element offirst type is, as also indicated in FIG. 4 a, 4 b, 5 a, 5 b, at leastsectionally, convex relative to the imaginary cross sectional plane XYextending between said coupling elements 24 ₁, 24 ₂, namely as seen fromthe cross sectional plane XY. As a result, a small change of therelative separation of the measuring tubes, for instance, as a result ofthermally related strain, is accommodated, and, indeed, while largelypreventing elevations of mechanical stresses influencing the oscillatorybehavior of the tube arrangement significantly.

In case required, furthermore, mechanical stresses and/or vibrationspossibly or at least potentially caused by the vibrating, especially inthe mentioned manner, relatively large dimensioned, measuring tubes atthe inlet side or at the outlet side in the transducer housing can e.g.be minimized by connecting the four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18₄ with one another mechanically at least pairwise on the inlet side andon the outlet side, in each case, by means of coupling elements servingas so-called node plates—in the following referred to as couplingelements of second type. Moreover, by means of such coupling elements offirst type, be it through their dimensioning and/or their positioning onthe measuring tubes, mechanical eigenfrequencies of the measuring tubesand, thus, also mechanical eigenfrequencies of the tube arrangementformed by means of the four measuring tubes including thereon placed,additional components of the measuring transducer, consequently also thenatural eigenfrequencies of its V-mode and its X-mode, respectively,and, thus, also the oscillatory behavior of the measuring transducer asa whole can, with targeting, be influenced.

The coupling elements of second type serving as node plates can, forexample, be thin plates, or washers, manufactured especially from thesame or a similar material as the measuring tubes, which, in each case,corresponding with the number and the outer dimensions of the measuringtubes to be coupled with one another, are provided with bores, in givencases, supplementally, slitted to the edge, so that the washers canfirst be mounted onto the respective measuring tubes 18 ₁, 18 ₂ and 18₃, 18 ₄, respectively, and, in given cases, thereafter still be bondedto the respective measuring tubes, for example, by hard soldering orwelding.

Accordingly, the tube arrangement comprises in an additional embodimentof the invention, a first coupling element 24 ₁ of second type, forexample, a plate shaped, first coupling element 24 ₁ of second type,which—as directly evident from FIGS. 4 a, 5 a, 5 b, 6 a—is affixed onthe inlet side to the first measuring tube and to the second measuringtube and spaced from the first flow divider for forming inlet-sideoscillation nodes at least for vibrations, especially also bendingoscillations, for instance, those in the mentioned V-mode, of the firstmeasuring tube and for thereto opposite equal vibrations of the secondmeasuring tube, as well as a second coupling element 24 ₂ of secondtype, for instance, one constructed equally to the first couplingelement, which is affixed on the outlet side to the first measuring tube18 ₁ and to the second measuring tube 18 ₂ and spaced from the secondflow divider 20 ₂ for forming outlet-side oscillation nodes forvibrations, especially also bending oscillations, thus those in thementioned V-mode, or X-mode, of the first measuring tube 18 ₁ and forthereto opposite equal vibrations of the second measuring tube 18 ₁.Equally, the tube arrangement includes a third coupling element 25 ₃ ofsecond type (for instance one, in turn, plate shaped, and, respectively,constructed equally to the first coupling element 24 ₁ of second type)affixed on the inlet side to the third measuring tube and to the fourthmeasuring tube and spaced from the first flow divider for forminginlet-side oscillation nodes for vibrations, especially the mentionedbending oscillations, of the third measuring tube and for theretoopposite equal vibrations of the fourth measuring tube, as well as afourth coupling element 25 ₄ of second type, for instance, oneconstructed equally to the first coupling element 25 ₁ of second type,affixed on the outlet side to the third measuring tube and to the fourthmeasuring tube and spaced from the second flow divider for formingoutlet-side oscillation nodes for vibrations, for instance, thementioned bending oscillations, of the third measuring tube and forthereto opposite equal vibrations of the fourth measuring tube.

The four aforementioned coupling elements 25 ₁, 25 ₂, 25 ₃, 25 ₄ ofsecond type, in an additional embodiment of the invention, are, as alsodirectly evident from the combination of FIGS. 4 a, 4 b, 5 a, 5 b, 6 a,6 b, in each case, affixed to exactly two, otherwise, however, to noothers of the four measuring tubes, so that, as a result, the first andsecond coupling elements 25 ₁, 25 ₂ of second type are affixed only tothe first and second measuring tubes and the third and fourth couplingelement 25 ₃, 25 ₄ of second type are affixed only to the third andfourth measuring tubes. As a result of this, the tube arrangement,consequently also the measuring transducer, can be manufactured e.g. ina manner such that, first, the first and second coupling elements 25 ₁,25 ₂ of second type are affixed, in each case, to the (henceforth) firstand second measuring tubes 18 ₁, 18 ₂ for forming a first measuring tubepackage and the third and fourth coupling elements 25 ₃, 25 ₄ of secondtype affixed, in each case, to the (henceforth) third and fourthmeasuring tubes 18 ₃, 18 ₄ for forming a second measuring tube package.Then, it is possible to join together for the tube arrangement the twomeasuring tube packages at a later point in time, for instance, directlybefore or also first after insertion of the two measuring tube packagesinto the mentioned tubular middle segment 7 _(1A) of the (henceforth)transducer housing, by corresponding affixing of the first and secondcoupling elements 24 ₁, 24 ₂ of first type to each of the two measuringtube packages, for instance, interim, in each case, to at least one ofthe measuring tubes 18 ₁, 18 ₂ of the first measuring tube package andto at least one of the measuring tubes 18 ₃, 18 ₄ of the secondmeasuring tube package. This has—especially also for the mentioned case,in which the measuring transducer is designed for large nominaldiameters of more than 100 mm, in spite of the relatively largedimensions of its components, consequently, of the tube arrangement, thetransducer housing, the flow dividers, etc.—the advantage, that the, asa result, relatively spread-out tube arrangement needs to be handled asa total piece only at a relatively late point in the time of the totalmanufacturing process. Moreover, this permits use of long existant,conventional measuring transducer technology for double tubearrangements, which brings a considerable reducing of the manufacturing-and inventory costs. In case required, the coupling elements 25 ₁, 25 ₂,25 ₃, 25 ₄ can, however, also in corresponding manner, in each case, beaffixed to all four measuring tubes, for example, also in the case, inwhich the measuring transducer is designed for relatively small nominaldiameters of 50 mm or less.

In the example of an embodiment shown here, the first coupling element25 ₁ of second type is affixed both to a—here sectionallybent—inlet-side tube segment of the first measuring tube 18 ₁ extendingbetween the first flow divider 20 ₁ and the first coupling element 24 ₁of first type as well as also to an inlet-side tube segment of thesecond measuring tube 18 ₂ extending equally between the first flowdivider 20 ₁ and the first coupling element 24 ₁ of first type, and thesecond coupling element 25 ₂ of second type is affixed both to a—herelikewise sectionally bent—outlet-side tube segment of the firstmeasuring tube 18 ₁ extending between the second flow divider 20 ₂ andthe second coupling element 24 ₂ of first type as well as also to anoutlet-side tube segment of the second measuring tube 18 ₂ extendingequally between the second flow divider 20 ₂ and the second couplingelement 24 ₂ of first type. In analogous manner, the third couplingelement 25 ₃ of second type is affixed both to a—here likewisesectionally bent—inlet-side tube segment of the third measuring tube 18₃ extending between the first flow divider 20 ₁ and the first couplingelement 24 ₁ of first type as well as also to an inlet-side tube segmentof the fourth measuring tube 18 ₄ extending equally between the firstflow divider 20 ₁ and the first coupling element 24 ₁ of first type andthe fourth coupling element 25 ₄ of second type is affixed both toa—here, in turn, sectionally bent—outlet-side tube segment of the thirdmeasuring tube 18 ₃ extending between the second flow divider 20 ₂ andthe second coupling element 24 ₂ of first type as well as also tp anoutlet-side tube segment of the fourth measuring tube 18 ₄ extendingequally between the second flow divider 20 ₂ and the second couplingelement 24 ₁ of first type. This, especially, in such a manner that—asdirectly evident from the combination of FIGS. 4 a, 4 b, 5 a, 5 b—atleast the first and fourth coupling elements of second type are parallelto one another and at least the second and third coupling elements ofsecond type are parallel to one another. Each of the four aforementionedcoupling elements 25 ₁, 25 ₂ of second type, especially ones constructedequally to one another, is, according to an additional embodiment of theinvention, additionally embodied plate shaped, for example, in such amanner, that it has, in each case, a rectangular basic shape, or,however, as shown in FIGS. 4 a, 4 b, a more oval basic shape. Asadditionally evident from the combination of FIGS. 4 a, 4 b, 5 a, 5 b,the four coupling elements 24 ₁, 24 ₂ 24 ₃, 24 ₄ can additionally be soembodied and so placed in the measuring transducer, that they arearranged symmetrically relative to the imaginary longitudinal sectionplane YZ and pairwise symmetrically relative to the imaginarylongitudinal section plane XZ and relative to the imaginary crosssectional plane XY. As a result, thus, a center of mass of each of thecoupling elements of second type, in each case, has the same distance toa center of mass of the tube arrangement. It can additionally, in thesense of a still simpler and still more exact adjusting of theoscillatory behavior of the measuring transducer, be quite advantageous,when the measuring transducer has, as, for example, provided in US-A2006/0150750 and as indicated in FIGS. 4 a, 4 b, 5 a, 5 b, moreover,still other coupling elements of the aforementioned type acting as nodeplates, for example, thus, in total, 8 or 12 coupling elements of secondtype.

As schematically presented in FIGS. 5 a and 5 b, the tube form of eachof the measuring tubes together with a minimum distance between thefirst and second coupling elements of second type—consequently thus inthe case of application of 8 or more of such coupling elements, thecoupling elements of second type lying on the in- and outlet sides, ineach case, nearest the center of mass of the tube arrangement, insofar,thus the coupling elements of second type innermost on the in- andoutlet sides, in each case, a wanted oscillatory length, L_(18x), ofeach of the measuring tubes. The wanted oscillatory length, L_(18x), ofthe respective measuring tubes corresponds, in such case, as alsoschematically presented in FIGS. 5 a and 5 b, in such case, to a lengthof the section of the bent line of the said measuring tube extendingbetween the two coupling elements 25 ₁, 25 ₂ of second type, whereinaccording to an additional embodiment of the invention, the couplingelements of second type are so placed in the measuring transducer, that,as a result, the wanted, oscillatory length of each of the measuringtubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ amounts to less than 3000 mm, especiallyless than 2500 mm and/or more than 800 mm. Alternatively, or insupplementation, it is additionally provided to so construct themeasuring tubes and to so arrange the coupling elements of first type,that all four measuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄, as a result, havethe same wanted, oscillatory length, L_(18x). According to an additionalembodiment of the invention, additionally, the first measuring tube andthe second measuring tube are, at least in the region extending betweenthe first coupling element of second type and the second couplingelement of second type—consequently thus in their respective wanted,oscillatory lengths—parallel to one another, and also the thirdmeasuring tube and the fourth measuring tube are, at least in the regionextending between the third coupling element of second type and thefourth coupling element of second type—consequently thus theirrespective wanted, oscillatory lengths—parallel to one another.

For creation of an as compact as possible measuring transducer ofsufficiently high oscillation quality factor and high sensitivitycoupled with an as little as possible pressure drop, according to anadditional embodiment of the invention, the measuring tubes 18 ₁, 18 ₂,18 ₃, 18 ₄ are, matched to the mentioned, wanted, oscillatory length, sodimensioned, that a caliber to oscillatory length ratio D₁₈/L_(18x) ofthe measuring transducer, defined by a ratio of the caliber D₁₈ of thefirst measuring tube to the wanted, oscillatory length L_(18x) of thefirst measuring tube, amounts to more than 0.03, especially more than0.05 and/or less than 0.15. Alternatively, or in supplementation, tothis, according to an additional embodiment of the invention, themeasuring tubes 18 ₁, 18 ₂, 18 ₃, 18 ₄ are, matched to the abovementioned installed length L₁₁ of the measuring transducer, sodimensioned, that an oscillatory length to installed length ratioL_(18x)/L₁₁ of the measuring transducer, defined by a ratio of thewanted, oscillatory length L_(18x) of the first measuring tube to theinstalled length L₁₁ of the measuring transducer, amounts to more than0.55, especially more than 0.6 and/or less than 1.5. According to anadditional embodiment of the invention, the oscillation sensors are,matched to the wanted oscillatory length, so arranged in the measuringtransducer, that a measuring length to oscillatory length ratioL₁₉/L_(18x) of the measuring transducer, defined by a ratio of thementioned measuring length L₁₉ of the measuring transducer to thewanted, oscillatory length L_(18x) of the first measuring tube, amountsto more than 0.3, especially more than 0.4 and/or less than 0.95.Moreover, the measuring length, L₁₉, and/or measuring length tooscillatory length ratio L₁₉/L_(18x) can, moreover, also be more exactlydetermined according to criteria proposed in assignee's notpre-published international applications PCT/EP2010/058797 andPCT/EP2010/058799 for determining optimum measuring lengths, or optimummeasuring length to oscillatory length ratios for measuring transducersof vibration-type.

For lessening possible cross sensitivities of the measuring transduceron pressure, especially also in the case of an as high as possiblenominal diameter to installed length ratio D₁₁/L₁₁ of greater than 0.1and an as low as possible oscillatory length to installed length ratioL_(18x)/L₁₁ of less than 1.5, in advantageous manner, additionally,annular stiffening elements can be used on the measuring tubes, of whicheach is so placed on exactly one of the measuring tubes 18 ₁, 18 ₂, 18₃, 18 ₄, that it grips around such along one of its, especially circularorbiting, imaginary peripheral lines; compare, for this, also theinitially mentioned U.S. Pat. No. 6,920,798. Especially, it can, in suchcase, be of advantage, when on each of the measuring tubes 18 ₁, 18 ₂,18 ₃, or 18 ₄, at least four such stiffening elements, especiallyequally constructed stiffening elements, are placed. The stiffeningelements can, in such case, for example, be so placed in the measuringtransducer 11, that two adjoining stiffening elements mounted on thesame measuring tube have a separation from one another, which amounts toat least 70% of a pipe outer-diameter of said measuring tube, at most,however, 150% of such pipe outer-diameter. Proved as especially suitablehas been, in such case, a separation from one another of neighboringstiffening elements lying in the range of 80% to 120% of the pipe-outerdiameter of the respective measuring tube 18 ₁, 18 ₂, 18 ₃, or 18 ₄.

Through the application of four instead of, such as to this point, twobent measuring tubes flowed-through in parallel, it is then alsopossible to manufacture, cost effectively, measuring transducers of thedescribed type also for large mass flow rates, or with large nominaldiameters of far over 250 mm, on the one hand, with an accuracy ofmeasurement of over 99.8% at an acceptable pressure drop, especially ofless than 3 bar, and, on the other hand, to keep the installed mass, aswell as also the empty mass, of such measuring transducers sufficientlyin limits, that, in spite of large nominal diameter, manufacture,transport, installation, as well as also operation can always stilloccur economically sensibly. Especially also through implementing ofabove explained measures for further developing theinvention—individually or also in combination—, measuring transducers ofthe type being discussed can also, in the case of large nominaldiameter, be so embodied and so dimensioned, that a mass ratio of themeasuring transducer, as defined by a ratio of the mentioned empty massof the measuring transducer to a total mass of the tube arrangement canbe kept directly smaller than 3, especially smaller than 2.5.

1-51. (canceled)
 52. A measuring transducer of vibration-type forregistering at least one physical, measured variable of a flowablemedium guided in a pipeline and/or for producing Coriolis forces servingfor registering a mass flow rate of a flowable medium guided in apipeline, said measuring transducer comprising: a transducer housingwith an inlet-side, first housing end formed by means of an inlet-side,first flow divider including four, mutually spaced, flow openings andwith an outlet-side, second housing end formed by means of anoutlet-side, second flow divider including exactly four, mutuallyspaced, flow openings; a tube arrangement including four, curved, orbent measuring tubes, which are connected to the flow dividers forguiding flowing medium along flow paths connected in parallel, of which:a first measuring tube opens with an inlet-side, first measuring tubeend into a first flow opening of the first flow divider and with anoutlet-side, second measuring tube end into a first flow opening of thesecond flow divider, a second measuring tube opens with an inlet-side,first measuring tube end into a second flow opening of the first flowdivider and with an outlet-side, second measuring tube end into a secondflow opening of the second flow divider, a third measuring tube openswith an inlet-side, first measuring tube end into a third flow openingof the first flow divider and with an outlet-side, second measuring tubeend into a third flow opening (20 _(2C)) of the second flow divider anda fourth measuring tube opens with an inlet-side, first measuring tubeend into a fourth flow opening of the first flow divider and with anoutlet-side, second measuring tube end into a fourth flow opening of thesecond flow divider; and an electro-mechanical exciter mechanism forproducing and/or maintaining bending oscillations each of the fourmeasuring tubes, wherein: the two flow dividers are so embodied andarranged in the measuring transducer, that an imaginary first connectingaxis of the measuring transducer imaginarily connecting the first flowopening of the first flow divider with the first flow opening of thesecond flow divider extends parallel to an imaginary second connectingaxis of the measuring transducer imaginarily connecting the second flowopening of the first flow divider with the second flow opening of thesecond flow divider, and that a imaginary third connecting axis of themeasuring transducer imaginarily connecting the third flow opening ofthe first flow divider with the third flow opening of the second flowdivider extends parallel to an imaginary fourth connecting axis of themeasuring transducer imaginarily connecting the fourth flow opening ofthe first flow divider with the fourth flow opening of the second flowdivider; the measuring tubes are so embodied and arranged in themeasuring transducer, that the tube arrangement exhibits lying bothbetween the first measuring tube and the third measuring tube andbetween the second measuring tube and the fourth measuring tube a firstimaginary longitudinal-section plane, and that the tube arrangementexhibits perpendicular to its imaginary first longitudinal-section planeand extending both between the first measuring tube and second measuringtube and between the third measuring tube and fourth measuring tube asecond imaginary longitudinal-section plane, and that the tubearrangement exhibits a natural bending oscillation mode of first type,in which mode: the first measuring tube and the second measuring tubeexecute, relative to the second imaginary longitudinal section plane,opposite equal bending oscillations about, in each case, a static restposition associated with the respective measuring tube; and the thirdmeasuring tube and the fourth measuring tube execute, relative to thesecond imaginary longitudinal section plane, opposite equal bendingoscillations about, in each case, a static rest position associated withthe respective measuring tube, in such a manner: that, relative to thesecond imaginary longitudinal section plane, said bending oscillationsof the first measuring tube are also opposite equal to said bendingoscillations of the third measuring tube; and that, relative to thesecond imaginary longitudinal section plane, said bending oscillationsof the second measuring tube are also opposite equal to said bendingoscillations of the fourth measuring tube; and wherein the excitermechanism is adapted to excite the bending oscillation mode of firsttype.
 53. The measuring transducer as claimed in claim 52, wherein: thetube arrangement has a natural bending oscillation mode of second type,in which the first measuring tube and the second measuring tube execute,relative to the second imaginary longitudinal section plane, oppositeequal bending oscillations about, in each case, a static rest positionassociated with the respective measuring tube, and the third measuringtube and the fourth measuring tube execute, relative to the secondimaginary longitudinal section plane, opposite equal bendingoscillations about, in each case, a static rest position associated withthe respective measuring tube, in such a manner: that, relative to thesecond imaginary longitudinal section plane, said bending oscillationsof the first measuring tube are also opposite equal to said bendingoscillations of the fourth measuring tube; and that, relative to thesecond imaginary longitudinal section plane, said bending oscillationsof the second measuring tube are also opposite equal to said bendingoscillations of the third measuring tube.
 54. The measuring transduceras claimed in claim 53, wherein: an eigenfrequency of the bendingoscillation mode of first type differs from an eigenfrequency of thebending oscillation mode of second type.
 55. The measuring transducer asclaimed in claim 53, wherein: the exciter mechanism is adapted to excitethe bending oscillation mode of second type.
 56. The measuringtransducer as claimed in claim 52, wherein: the two flow dividers are soembodied and arranged in the measuring transducer, that a firstimaginary longitudinal section plane of the measuring transducer, withinwhich the first imaginary connecting axis and the second imaginaryconnecting axis extend, is parallel to a second imaginary longitudinalsection plane of the measuring transducer, within which the imaginarythird connecting axis and the imaginary fourth connecting axis extend.57. The measuring transducer as claimed in claim 56, wherein: the twoflow dividers are so embodied and arranged in the measuring transducer,that a third imaginary longitudinal section plane of the measuringtransducer, within which the imaginary first connecting axis and theimaginary third connecting axis extend, is parallel to a fourthimaginary longitudinal section plane of the measuring transducer, withinwhich the imaginary second connecting axis and the imaginary fourthconnecting axis extend.
 58. The measuring transducer as claimed in claim57, wherein: the measuring tubes are so embodied and arranged in themeasuring transducer, that the second imaginary longitudinal sectionplane of the tube arrangement extends between the third imaginarylongitudinal section plane of the measuring transducer and the fourthimaginary longitudinal section plane of the measuring transducer. 59.The measuring system as claimed in claim 52, wherein: the tubearrangement exhibits an imaginary cross sectional plane perpendicularboth to the first imaginary longitudinal section plane as well as alsoto the second imaginary longitudinal section plane.
 60. The measuringtransducer as claimed in claim 59, wherein: each of the four measuringtubes exhibits a measuring tube peak, defined as greatest perpendiculardistance of the respective measuring tube from the first imaginarylongitudinal section plane, and the imaginary cross sectional plane cutseach of the four measuring tubes in its respective measuring tube peak.61. The measuring transducer as claimed in claim 52, wherein: the firstmeasuring tube exhibits a caliber, which equals a caliber of the secondmeasuring tube; and/or the four measuring tubes are of equalconstruction relative to a material of their tube walls, and/or relativeto their geometric tube dimensions; and/or a material of the tube wallsof the four measuring tubes at least partially comprises titanium and/orzirconium and/or stainless steel and/or duplex steel and/or super duplexsteel; and/or the transducer housing, the flow dividers and tube wallsof the measuring tubes, in each case, comprise steel.
 62. The measuringtransducer as claimed in claim 52, wherein: each of the four measuringtubes exhibits a caliber which amounts to more than 40 mm.
 63. Themeasuring transducer as claimed in claim 52, wherein: a middle segmentof the transducer housing is formed at least partially by means of astraight support tube.
 64. The measuring transducer as claimed in claim52, further comprising: a sensor arrangement reacting to vibrations ofthe measuring tubes for producing oscillation signals representingvibrations.
 65. A measuring system for measuring density and/or massflow rate of a medium flowing, at least at times, in a pipeline, saidmeasuring system comprising: a measuring transducer as claimed in claim52; and a transmitter electronics electrically coupled with themeasuring transducer for activating the measuring transducer and forevaluating oscillation signals delivered by the measuring transducer.66. The measuring system as claimed in claim 65, wherein: the fourmeasuring tubes, excited by the exciter mechanism, execute, duringoperation, simultaneously, bending oscillations in said bendingoscillation fundamental mode of first type.
 67. The measuring system asclaimed in claim 66, wherein: the transmitter electronics, based onelectrical excitation power converted in the exciter mechanism,generates a viscosity measured value representing viscosity of theflowing medium; and/or the transmitter electronics, based on oscillationsignals delivered by the measuring transducer, generates a mass flowmeasured value representing mass flow rate of the flowing medium and/ora density measured value representing density of the flowing medium. 68.The use of a measuring transducer as claimed in claim 52 for measuringdensity and/or mass flow rate and/or viscosity and/or Reynolds number ofa medium flowing in a process line.
 69. The use of a measuring system asclaimed in claim 65 for measuring density and/or mass flow rate and/orviscosity and/or Reynolds number of a medium flowing in a process line.